My friend, the murder statistic: Domestic violence victims might seem like just a number - until it's someone you know

Last summer, a 29-year-old woman was stabbed repeatedly and killed in her home in the early hours of a July morning. It quickly transpired that she had been in contact with the police several times in the days before her death. Headlines focused mostly on her appearance: "Beauty queen stabbed", "Model killed". Pictures of her smiling face dominated coverage alongside the gory details, though these varied even from site to site; surely a traumatised child cannot be discovered both screaming and standing in shocked silence beside her mother's body? Amid lurid and sensationalised speculation just one simple, indisputable fact remained: a woman was dead.

In late May, David Gikawa, 39, was sentenced to life for her premeditated murder. The victim knew him. The victim had lived with him, tolerated his abuse for a time, moved away, been persuaded to allow him back – to try again for the sake of their two-year-old child – and then finally ended their relationship, which he would not accept and so he killed her. Her unique life and identity risk being swallowed by the story of her death, background noise that seems familiar rather than shocking, outrage absent in the face of helpless acceptance. It presents as almost consensual, nobody else's business. An incident between two people. Domestic. Ex-partner. No one else involved.

Except that I feel involved. Her name was Linah Keza and she was my friend.

During his month-long trial at the Old Bailey, her killer did all he could to blame, discredit and misrepresent her, making an already devastating situation for her family and friends much worse. The question at the heart of his defence was not the undisputed issue of who entered her home and knifed her to death – because he had been interrupted in the act by a brave neighbour who kicked down the door – but whether she deserved to die. Whether she was a bad woman who could drive a good man to kill. She was on trial, even in her grave. Gikawa refused to admit any responsibility, despite extensive reports of his stalking, monitoring her messages, controlling her finances and threats of harm. Thankfully, he was not believed. Passing a sentence of life imprisonment, Judge Michael Topolski described his actions as: "Not a loss of control, but a loss of temper, and an act of calculated, jealous revenge on an innocent woman whose life you had made a fearful misery."

Linah had been widely loved. We first crossed paths several years earlier while living in the Midlands, not long after her arrival in the UK, and had become friends at a church. We both relocated to London at the same time; she was pregnant and about to move in with the man who would later kill her. We would often catch up to talk and laugh about life, love and mutual friends, and coo over her lively and playful daughter. She loved conversation and exuded warmth and hospitality. "Come and see us soon," she would always insist when we said goodbye.

Online tribute pages had filled within hours of her death; shocked, grieving words from all over the world, particularly her former home of Rwanda. Linah was unique: optimistic, ambitious, funny and dignified with gentleness and determination in equal measure. Words can't capture her laugh, her exclamations of surprise or the way she said her child's name. She reminded me of the supermodel Iman, a comment she waved away but upon seeing pictures of the African supermodel she became intrigued. She said I was the first person to tell her that she was beautiful – impartially, model beautiful – and she had become interested in what that could mean for her. She entered a Miss Africa contest and won. She decided that there should be a Miss Rwanda competition across Britain for those in the diaspora, and plans were under way when she died. She enthusiastically pursued modelling, though longed-for worldwide exposure was achieved only by her horrific death. She was a naturally gifted mother with a happy, clever, enquiring child for whom she wanted to do great things, and she was restless in wanting a better life for them both.

Her story could easily be one of silences and missing answers. She wasn't on Twitter – where threats are spat remotely, often anonymously, and responses are swift – and wouldn't have known how to make her voice heard in the wider world. Access to technology was dependent on her killer's presence in her life. In the times that he was absent, her flat would be stripped of ways to connect with the world, apart from perhaps a phone, but little more. She lived in a foreign land, known well only to those whom she called family here and overseas. Close-knit despite distance, frequently travelling miles to visit each other's homes and share their lives, rarely interacting with people such as me. I knew that her life was very different from mine, our friendship unlikely and our worlds disparate. Her life in Britain was marked by transience, vulnerability and unpredictable situations, anchored in relationships, not geography; her circumstances often beyond her control. She could be elusive, hard to keep track of. It was a game that maybe she didn't realise she was playing. Or maybe she did, trying to manage the actions of a violent man and stay alive.

When the MP Stella Creasy received a hideous image of a masked man clutching a knife with the words "I'm gonna be the first thing u see when u wake up", I experienced a lurching realisation that Linah's final experience may have been horribly similar, yet her threats were not splashed across the national news. They would have appeared, if anywhere, on phone screens seen only by a few, or repeated in desperate phone calls to people who might be able to make it stop. Linah's audience was not able to raise national outrage or change outcomes. The journalist Hadley Freeman reported surprise recently when four police officers paid her a visit after she received a tweeted bomb threat; she suspected she was not really in danger. Linah was alone when the threats became a reality – except for her killer, and their daughter, who saw it all – and no one came in time. It is not only how loud that we shout, but who is there to hear us and who has the power to act.

Charity worker Karen Ingala Smith launched the campaign "Counting Dead Women" to list all the women alleged to have died because of male violence. It was instantly sobering to realise that of the 75 who had lost their lives from 2 January to 31 July last year, when Linah was added to their number, only two stories were familiar to me. Some cases had mainstream media coverage, others just a couple of lines on local news sites: woman killed, man charged. That men kill women they know was unsurprising, barely newsworthy. Lives wiped out almost unmentioned just because they had once had a relationship with their killer.

It shouldn't be like this. A numbingly obvious statement, but one that cannot be shrugged off as though deaths are inevitable. More women die this way every year than cyclists are killed on UK roads – yet often their deaths are described as "isolated incidents". Sometimes violence can be seen before it happens, sometimes it is seen but not talked about, sometimes it is hidden until it explodes, but it is everyone's problem. It permeates expectations. Up close it awakens us to horror, though for many it is distant and hypothetical. Good intentions alone cannot offer protection and I cannot honestly say that I understood how much danger Linah was in. Only a couple of people may have known that, and one of them created that danger. It is messy and even frightening to be so close to abuse and to realise that the systems and resources we rely on to protect those affected are sketchy and unreliable if they exist at all.

The underlying reasons why 143 women died from male violence in 2013 (and another 64 so far this year, according to Ingala Smith's tally) need to be talked about and attitudes exposed. Many of those women could have been my neighbour. Many on the list had names that were not of British origin. It would be easy to think that they were nothing to do with me, to read their stories and think that their deaths had come about because of an unfamiliar culture, one on which I wasn't qualified to comment or enter for fear of judging. Far less easy would be to confront my own ingrained, unconscious prejudices about women who become victims of men they knew. Flawed questions have become an inner voice: why had she let him into her life when he seemed troubled or when problems started? Why hadn't she pressed charges before? These are questions that I need to root out of my psyche. The silenced, destroyed women are not to blame. The real questions are for the men who kill them: why? What was going to happen if she had a life that didn't include you? Why did you believe she was yours to do with as you wished?

And for those who harbour similar urges, who wonder if their outbursts of violence were out of character: will you change? Will you go down the hard, hard road of admitting that you need help? That your understanding of women and relationships is so flawed, your own identity founded in something so fundamentally wrong, that you might kill people whom you claim to love?

And for all of us, perhaps unknowingly surrounded by people (yes, men can be victims too) experiencing this hidden darkness – often very hidden – we need to take it upon ourselves to learn the signs. We need men who are not violent, controlling or abusive to step up, speak out and create environments where this is not OK, and to help to open the eyes of abusive men to the fear and pain they cause. We must all learn how to deal with men who are abusive, even if they are your family or friends. We need to challenge the roots of a culture that says it's unavoidable, even natural, for men to behave this way.

I am in awe of those who spend their lives making sure that the stories of women who can no longer speak for themselves are heard, tirelessly telling an often indifferent world what is happening. It doesn't make for polite conversation, but silence makes us complicit. This violence diminishes us all, rips the heart out of families, ends lives and seems so far away until, suddenly, brutally, it isn't.

I wish Linah could tell you her own story. David Gikawa has tried to wipe her from the face of the earth and I, for one, will not allow that to happen. Yes, she is in the ground now, far away in Rwanda, and that is how her child speaks of her "old Mummy in the ground". A heartbreaking outcome for a woman so full of life and devoted to motherhood. A social worker helping Linah's daughter advised me to read a book called When Father Kills Mother. "Children who've seen this happen have stories to tell," she told me. They shouldn't have, though, should they?

The National Domestic Violence Helpline (0808 2000 247) is a 24-hour freephone service for women experiencing or concerned about domestic violence, their family, friends, colleagues or others calling on their behalf. nationaldomesticviolencehelpline.org.uk

Respect works with domestic-violence perpetrators, male victims and young people. If you are concerned about your own behaviour, or the behaviour of someone you know, it can be contacted on 0808 802 4040, by email at info@respectphoneline.org.uk, or through its website, respect.uk.net