Ten years ago, if anyone had told me they were postponing divorce "till the children are older" I'd have thought their words made perfect sense. Back then, my children were one, five, eight and 10. I wouldn't have been able to imagine the effect on them of hearing that their father and I were splitting up. Whose house would they live in? How would they cope without bedtime cuddles from both of us? What would weekends and holidays be like for them without the two of us around? So much better to postpone it, I'd have mused: by the time they were older and living their own lives, they'd hardly even notice the break-up.
Today, though, my elder daughters are almost 21 and 18 – and I now realise that, however hard it would have been for them to cope with a family split when they were younger, it would, if anything, be worse for them to have to face it now. And if I already knew that somewhere deep inside the fallout on the son of Chris Huhne and Vicky Pryce from their break-up, as tragically documented during last week's court case, only underlines the issues.
Peter Huhne was 18 when his parents' marriage ended. To the outside world he'd have looked, just as my daughters look, like adults. But inside he was sometimes still a child – just as my daughters are still sometimes children – and when things went sour between the two people who mattered most in the world to him, he found it very hard to handle. His passionate, angry text messages to his father, made public after Chris Huhne's guilty plea, lay bare his confusion and hurt and horror that the break-up could be happening – not only to them, but to him.
And that, really, is the point: divorce doesn't just happen to a couple, it also happens (if they have them) to their children. And it happens to those children whether they are babies or small children or big children or even adult children: because for most of us, our parents' marriage is the bedrock on which our lives are built. It's a vital part of our stability at any age: when I was in my 40s, the fact that my parents were still together (my father has since died) and the fact that they had a home together that I could visit and to which I could take my children gave a layer of certainty, of permanence, even at that stage of my life.
But if your parents' divorce is going to hit you at any age, it's probably going to hit you especially badly when you're a young adult.
"People make the assumption that because someone is legally an adult, they are emotionally an adult – but that's not true," says the Cambridge University psychologist Terri Apter, who has written extensively on the transition from adolescence to adulthood. "In fact, the brain doesn't become fully adult until the age of about 24. Until that stage, you're dealing with people who don't have the psychological hardiness of an adult: they can't properly plan ahead or master their impulses the way an adult can."
Being grown-up is often equated with leaving home – but, Apter says, this is a misunderstanding. "They may have physically left home for part of the year to study, but it's vitally important for them to be closely connected with their family and the home they grew up in. Of course they want to be independent, and they're practising independence, but being able to do that relies to a very large extent on knowing that their parents and their home are behind them."
So in other words, the existence of a dull, boring, samey old home being somewhere in the background gives young adults the confidence to strike out and try living in a different sort of way. But if that home and that family crumble, the story is very different: young people start to question everything they've come to know as true and strong and feeling the rug pulled from under them can lead them to question all sorts of assumptions in their lives. Suddenly, everything they thought was real isn't real. They start to wonder whether their parents ever loved one another, whether their marriage has been a total sham. They may feel guilt: did their parents stay together this long just because of them? And if so, what unhappiness has their existence heaped on them? Beyond that, Apter says, there's a kind of emotional displacement. Young adults don't need their parents in the way they did when they were children – but they still need lots of psychological support. They fall in and out of love, they have work crises, they struggle with what they're going to do with their lives, they fret about how they're going to afford a flat. All these problems need a lot of time and a lot of energy from their parents. And if those parents are caught up in their own problems and are negotiating the end of a long marriage, there won't be much emotional energy left to help their children.
Right through our lives, there's a sense in all of us that we have to be the "stars" where our parents are concerned. And divorcing parents, especially those going through messy divorces like the Huhnes's, take centre-stage and edge their children into the wings, every single time.
There's no doubt either that the ending of their parents' marriage has implications for the relationships their young adult children are embarking on. Research by the Joseph Rowntree Foundation found that people who were over 20 when their parents separated were more likely to have their own first partnership or marriage break up by the age of 33. And there are financial implications, too: when parents stay together, the family pot stays intact. Separated, their individual needs eat more quickly into their savings and there will be fewer funds to support children as they set out on their own lives and less for them when their parents eventually die.
It's all sobering stuff, especially given that the number of so-called "silver splitters" (couples whose marriages break up in their late 40s and 50s) is on the rise.
The bottom line is, if you've got children, ending a marriage is never going to be straightforward. But the important thing, Apter says, is knowing that's the case. "Everyone understands how much support young children need if their parents split up," she says. "But they need just as much support and help when they're adults as well – and providing that support makes a huge difference as to how their lives pan out."