Claudia Winkleman: Don't let your man near a nanny

So Ethan Hawke has just married his children's ex-nanny. Nice. Classy one there, Ethan. You couldn't have left the building and gone to a bar to chat someone up? When you considered having an affair you didn't think of casting your net a little further? You know, wider than your kitchen?

You didn't think of asking your friends if they knew any nice women who would go out for a secret cocktail and a flirt? You couldn't have joined a dating website? But no, you saw a pretty girl in the hallway one day who occasionally sang "The Wheels on the Bus" to your kids and you thought: "Yup. OK. You'll fit." You didn't even have to buy her a drink; you could just meet at the fridge and, um, open a beer, while your wife was looking the other way.

The ex-nanny is now seemingly about five minutes away from having Ethan's baby, and they're hitched. The nanny is still, uh, looking after the children – but just now every other weekend instead of all the time. And I'm presuming he no longer pays her. Well, maybe just in Cartier watches.

I feel sorry for Uma. Now that, along with: "Gosh, if only there was more of Lionel Blair on television," is a sentence I never thought I'd utter.

But let's be clear. There's no one worse your husband could leave you for. I think if I found my husband in bed with my sister, it would be a little disconcerting – yes, I'd probably need a lot of therapy and I'd try to kill them both, but at some point I'd like to think I'd get through the pain and somehow forgive them. Finding him with my best friend would be no fun, but you know, they already really like each other, she's very cute, they get on well on holiday and these things happen... But the NANNY?

No. Just no. Not in my lifetime, baby. When you ask someone to come into your house to help look after (let's be honest – raise) your children, it's a BIG DEAL. You interview probably more than 900 candidates, you get references, you watch them closely with your kids before you officially employ them. I mean, if Jaws spooked people a little bit about getting into the ocean, The Hand That Rocks the Cradle terrified every mother on the face of the earth.

Hiring someone to look after your children is about the most important thing you will ever do in your life. And you can forgive them for sometimes giving your kid a "hush, hush, don't tell Mummy" Mini Milk, and you can let the odd extra In the Night Garden viewing go. But sleeping with your husband is pushing it too far.

And here's the rub. If you're a working mother, you already feel like you're hiring a "replacement you". You think: "Well, if I can't always be there to tuck them into bed at night, it's great that Samantha/Lucy/insert name here can."

While this might be OK some of the time, the rest of it you will probably be riddled with guilt. You will spend endless nights awake in bed justifying to yourself why it's perfectly all right that you don't take them to the park every day and that sometimes they call the nanny "mummy".

And you will toss and turn and wonder whether you have made the right decision. At moments such as these, you might make a list of reasons why it's good that you are continuing to work and have a nanny rather than staying at home with them.

The list might look something like this:

a) I can't stay at home all day because I might go mad.

b) I like using my brain/having my own life.

c) I need to be financially independent from my husband.

d) I don't want my child and I to get on top of each other and argue. We will get on better if we have quality time together.

And you can bet that the big reason – the pièce de résistance, the all-time most popular reason for going back to work and getting someone in to help you look after your children – is this one:

e) I will have a more successful relationship with my husband if he respects me and if I manage to stay interesting to him. I will manage this through keeping a career and by not turning into a jelly-brained bore who can only discuss why Ludo doesn't like dried apricots any more.

Well, guess what: Ethan goes and blows that theory. He shoots that shit straight out of the water. While his superstar drop-dead-gorgeous movie actress wife was filming with Quentin Tarantino, when she was picking up $15m a movie, and when she was coming home with seriously interesting stories from her day at work, it turns out all he wanted was the smiley girl who sang "The Wheels on the Bus".

Now that's even scarier than Rebecca De Mornay.