The dilemma I have been married to my alcoholic husband for 14 years. We have a 13-year-old son, and two older kids from my previous marriage. I had an affair with a black man from 2007 until 2009. I had kept it a secret from my husband until he found out from my diary in 2010. Since then he has started drinking three or four bottles of wine a night and blames his drinking on me. He has been hospitalised and in rehab many times for his alcoholism.

Our son is suffering because when my husband drinks he gets aggressive and my son has to stand between us to stop him hitting me. I have seriously thought about leaving without a trace. Maybe my son will be happier without a mother who is so pathetic.

Mariella replies The current problems in your relationship are definitely connected to your husband’s alcoholism, but overshadowing all of them is the physical threat you are under. I’m surprised it took you so many paragraphs before mentioning his violence towards you.

Maybe it’s something you are ashamed of. You won’t be the first victim of a tormentor to see their own suffering as something they have brought on themselves, or as a reflection of their worth. That’s utterly untrue and I’m hoping you can see, when written in black and white, how misplaced such feelings are. Or perhaps you excuse his physical abuse as a side effect of his drinking. While the latter might to some extent be true, it doesn’t excuse or condone his behaviour. Next time he attempts to raise a hand to you it’s important you remain calm and call the police. It’s not your son’s job to stand between his parents, and continuing to foist that role on him will be doing him damage that I know you wouldn’t want to inflict.

In small steps, and with great courage, you must remove your son and yourself from this man’s grip

I’m hoping you can count on the support of your two adult children, because you need as big and as vocal a support network as you can muster. It’s an opportunity for your friends and family to provide real tangible back-up by showing him that they are unafraid and prepared to be your witnesses. You are definitely not alone: the statistics for domestic abuse in this country are staggering. You need to get your experience on the official record and the sooner you do, the quicker your rights will be established in this terrible situation.

First, you need to understand that there is no excuse at all for the behaviour you are being subjected to. It needs to stop and your future plans can be better established when you are in a place of safety. We say “until death us do part” when we tie the knot, but there really needs to be a sub-clause that exonerates us for instant departure in the event of violence, dangerous addiction and abuse of any kind. Rowing and raging may be an unpleasant sideshow in many relationships, but sustained abusive behaviour and particularly any form of physical threat is an immediate red card. If he won’t clear out of your home, you will have to.

There are many organisations that can support you, particularly the beleaguered Refuge (24-hour National Domestic Violence Helpline, 0808 2000 247) which, despite losing much of its government funding, does an incredible job in rescuing the victims of domestic abuse from harm.

You didn’t sign up for this experience and every day you accept it you are causing damage to both your son and yourself. This man’s drinking may be hard to live with, but his abuse is a total deal breaker.

In the circumstances I’m tempted to ignore you describing your ex-lover as a “black man” as though it was his skin-colour, rather than your affair, that provoked your spouse. Instead, I’m going to give you the benefit of the doubt; like the spouses of many abusers you are probably just trying to find blame in yourself for your abuser’s crimes against you.

If your husband considers your choice of lover a further insult then he’s even more monstrous than you have described. We’re not living in apartheid South Africa now, or in one of the many countries today where abuse at home is considered the divine right of husbands. Your lover’s racial make-up has absolutely nothing to do with the problems you are enduring today and it’s time you stopped looking for excuses.

In small steps, and with great courage, you must remove your son and yourself from this man’s terrible grip and, if you can, enlist friends and family to help you on your way. Most importantly contact Refuge who, with the sobering statistic of one in four women experiencing domestic violence in their lifetime, are pretty well qualified to give you practical help and advice.

If you have a dilemma, send a brief email to mariella.frostrup@observer.co.uk. Follow her on Twitter @mariellaf1