Diana Melly: I have an open marriage but there are limits, Jude

But the jealousy question is a fair one. My husband, the critic and jazz singer George Melly, has slept with scores of women since we've been together, and has enjoyed several close affairs that have lasted years. Some of those women have slept at my house. How can I not care?

Well, I used to. I was terribly neurotic and possessive. For the first nine years of our marriage I saw a psychiatrist once a week and refused to let George out of my sight. He was amazing - protective and patient - but underneath he was sick of it all, understandably.

As it turned out, I was the first to have an affair. Years later George told me that he did everything he could to encourage me because he knew that then he could as well. I hadn't had much of a teenage life and this was great fun. Max was 18. George made it clear that he knew what was going on - in fact I think I even asked his permission. When George started an affair of his own, I was pleased for him. All that neurotic jealousy had gone.

I do believe there is a non-neurotic, justified kind of jealousy. I think what Jude Law did is appalling because the children are involved. That is such a betrayal. It as if the children's loyalty is also being abused. There are unspoken limits. Best friends, the nanny and step-daughters. But I don't consider that George ever betrayed me. I always knew what was happening and quite often I liked the women.

Perhaps the most important factor, though, is that George and I stopped sleeping together. I wasn't ever able to do that thing of sleeping with more than one person at a time and sexual jealousy has never been an issue since.

George has had long relationships with three women. I like, and often meet up with, two of them, although we're not exactly friends. But the other one I actively dislike. She is the only one he has ever suggested he may leave me for, although that is not why I dislike her (really). She is a dangerous influence. He drinks too much when he is with her and she has left threatening messages on my answerphone.

On the whole, I always assumed we'd stay together, come what may. On one of the two occasions when he was going to leave me, he changed his mind almost immediately, but didn't tell me for a few days. I had been devastated but when he called me to tell me he was staying he said, "Sorry, I've been meaning to phone to tell you, but I've been terribly busy."

With her, I do allow myself to have little revenges. Once I Tippexed a date with her out of his diary. Another time, when he was going out to lunch with her, I arranged for three of his favourite people to come to lunch - with me. "What a pity you won't be here for it," I told him as I sent him on his way.

One of the great benefits of an open marriage is honesty. We have nothing to hide. There are no awful surprises. George, unlike me, was never someone who was going to be satisfied with the sexual attentions of one woman. Does that mean I have over-indulged him? I don't think you can ignore the fact that men have more testosterone. George, like an awful lot of men, just won't grow up. It's so pathetic. I get very cross when men talk about being "a bit of a Peter Pan". Why on earth shouldn't they grow up? Not that there's a great deal one can do about it. And like so many really driven men, George wants as much of everything as he can manage, not excluding women. On top of which, he wants - demands - a great deal of attention and admiration. Our children, Candy and Tom, are not like that. Both are happily married and I think will always remain monogamous.

But I am not a doormat. George gets quite a hard time at home. If he tells a joke, I say: "George you know perfectly well I'm not interested in jokes." I'm the opposite of a fawning, adoring wife and am very bossy. My nickname is the wing commander.

George and I have been terribly lucky that it's worked out. I think marriage is hard and an open marriage has its particular problems. But the way I see it, if we hadn't agreed to the sort of marriage we had, we wouldn't be together now and I think that would be a shame. He drives me mad but I am very pleased I am still married to him.

'Take A Girl Like Me' by Diana Melly, is published by Chatto & Windus on 4 August