Forget what Doctor Foster's Gemma and Simon are doing to each other - it's their son who'll suffer the most

We watched the cunning, conniving Gemma and Simon from the edge of our seats. Whose side were we on? This was gripping television.

What was extremely uncomfortable, however, was watching the impact of this couple’s twisted and obsessive hatred for each other on their son, Tom.

For me, as a clinical psychologist working with children and families, watching Doctor Foster felt like a busman’s holiday – because this really happens. While Gemma’s behaviour feels Machiavellian, we cheer when she gets one up on her ex, who may have betrayed her by being unfaithful in series one but has spent this series being sociopathic.

But what are the costs as this hateful couple slug it out? As realistically shown by Tom, the ultimate cost is to their child.

Gemma and Simon are, to me, an example of the worst kind of parents, damaging their child behind the mask of respectability. Indeed, while they may not be overtly abusing their child, the psychological impact of their behaviour will cause him lifelong difficulties. And so while they might rationalise that they are fighting it out in order to protect their son from each other, in fact they are jointly complicit in their de facto abuse of him.

As parents, Gemma and Simon are dire; watching Tom being buffeted back and forth by his obsessively vengeful parents was extremely unsettling. Indeed, while Gemma may justify her actions based on the treatment she has suffered from Simon, I would argue that nothing justifies what her son is witnessing, and indeed hearing – their angry, post-divorce sado-masochistic sex – through the thin walls of the old family home.

I have worked with many families that are going through separation and divorce. While in a perfect world all children would be raised by both their parents together, it is well understood that children suffer more in households with two unhappy parents than when raised by separated but happy parents.

When I work with couples who, despite being apart, continue to fight, I despair. The toxicity of this conflict means that children are never free from the hostilities that ended their parents’ marriage and often, as they shuttle between two homes, have to endure the “Whose side are you on” position that they are often put in.

It is not their responsibility that the parents are unable to sustain a relationship, so why should it become their responsibility to mediate between two adults behaving like emotionally unintelligent children?

Conflict is damaging, especially conflict happening between the two people children love most in their world. Indeed, children are affected by the mental state and behaviour of their parents and, for children like Tom (who we have already seen displaying aggressive and abusive behaviour), the outcomes can include depression, anxiety and substance misuse.

Gemma and Simon’s legacy to their son is likely to be him finding it difficult to trust others, having difficulties forming and sustaining relationships and anger issues. Their narcissistic preoccupation with revenge means they ignore his needs while he is caught up in an emotionally damaging tug of war.

For Tom, Philip Larkin’s famous line about how your mum and dad mess you up is prophetically accurate. Thankfully, this is drama, a fiction; the tragedy is that for many children such experiences are painfully all too real.

Doctor Foster is on 9pm tonight, BBC2

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