Ou gave me the email link to the newspaper report that somebody sent you (the girl punched by your ex?), so I know all the tawdry details of this case.

DEAR BEL,

I MET my partner at 20 and in 20 years we had four children. He was a known ‘bad boy’ — which I liked as a challenge.

But he became cruel and badtempered, and spent hours addicted to online gambling and worse. He lost his job, increased his gambling and became physically abusive, hitting and even spitting in my face.

The mental abuse was far worse. I became a nervous wreck. He’d go off for days and nearly missed the birth of our (unplanned) fourth child.

When the baby was one, he told the children he was leaving, before telling me. Obviously, they were upset. I was left with four young children and no job, just before Christmas.

A few weeks later I was woken at 6am by two policemen looking for him. They gave me a number and said that if he turns up, I must call. Days later he arrived to see the children and I asked about the police. He said he had driven off from a petrol station by mistake, which I believed. He told me he had been sleeping in the back of a car. The police rang. He left.

One day I was looking at my emails and saw a strange message with a link. I clicked and it took me to a local newspaper article about a violent incident at a swingers party.

To cut it short, he was seeing a girl in another town and left me to live with her. At a swingers party, she went upstairs with six men and two women and he became jealous. He punched her in the face several times and was arrested and later convicted.

My children are now 20, 18, 16 and 14. They think their dad is great. He sees them just once or twice a year and pays very little towards their care as he has a low-paid job.

Sometimes, when I’m frustrated with him, I might say something negative (nothing serious — just a tut or ‘Ask your dad to pay for that’) and immediately they take his side.

I find this really frustrating. I was going to tell the children the whole truth when they were 18 but that time has passed.

I feel that they should know but at the same time I know it would hurt them and I don’t want to do that to them. Bel — would you tell them or just leave it?

LINDA

YWhen this girl went upstairs for group sex he was actually having sex downstairs with somebody else but still got jealous. Yuck, they all deserve each other, eh? But neither you nor your family deserved such a sleazebag in your life.

I can see why, if your children sentimentalise the rotten father they barely see, it must irritate you a lot. But they need to, don’t they?

In my days as a young reporter in some of Britain’s most deprived areas, I learned how even ill-treated children will cleave to the worst of parents, so great is their craving for love. I suggest you interpret their habit of defending their father as an indication of their wish for a ‘real dad’ and not as disloyalty to you.

of course this will be hard, as you have spent so many years coping alone and remember the time when he was present with nervous horror at what he put you through. Yet they still need their illusion of a ‘father’.

That brings us to the real dilemma. How important within a family is the whole truth? We start with a vital question about motive — in other words, why exactly you would be telling

your children facts about their father? If your aim is actually to punish him by completely souring their vision of a distant, almost imaginary dad, then the truth becomes no more than a form of vengeance.

For if they were to read the news link to that story about his squalid sex life and bullying violence, then surely no illusions could be left.

But revenge is no justification for inflicting pain and shame on your children.

Is there another reason to tell them? You could answer that as adults they need to be warned about his past, just in case some stranger spills the beans one day, and then they turn and blame you for keeping the shameful secret. For lying by omission. This is surely valid. People can blame the keeper of a secret, especially if she is near, while the actual sinner is far away.

Even in your longer letter you say nothing about your ex’s life since that arrest, subsequent fine and community service order.

It could be that he is a reformed character — and that too might have a bearing on your irritation.

The only thing that I can suggest is a compromise. If you can satisfy yourself that your motive is not vengeance but to treat your children as adults, then you might proceed with caution and have a long talk with the older two.

Your attitude should be calm and sad as you emphasise that although he hurt and shamed you, he is still their father.