Our bedrooms were separated by a thin partition wall, through which I’d hear Tom playing retro hits by Blondie and The Cure well into the small hours. Sometimes I’d touch my palm to the wall and almost feel him breathing in the bed on the other side.

I wasn’t like other teenage girls. I didn’t care about the things they cared about: boys, clothes, approval. I couldn’t afford to let myself care about anything. If I allowed myself to feel, the emotion uppermost would be rage.

Rage at my father, a violent narcissist who took pleasure in reducing my mother to a cowering wreck with his fist and his words. Rage at my mother, for letting herself be used as a punchbag and coming back for more again and again.

Rage at my own powerlessness.

In the absence of feeling, I’d do almost anything to force a jolt of emotion. I climbed higher up the chestnut tree to shake down conkers than any of the boys. I scaled a mobile phone mast for a dare. When I was thirteen, I sneaked out of the house in the middle of the night to climb the fence into a nearby railway yard, so that I could run the roofs of the trains parked in the sidings just for the hell of it; a fall into the gaps between carriages would have broken my neck. I hung onto the rear bumpers of passing cars on my skateboard to get a lift up the hill to our road. I was fearless, a daredevil, the leader of the pack. And Tom was my wingman.

Then – and now.

He never asked what I used to get up to when I disappeared, sometimes for days at a time, in the early years of our marriage.

We called these absences my ‘prison breaks’. Afterwards, when I returned to him, the restlessness that fuelled me would be sated for a while. Without me ever having to discuss it with him, Tom understood.

Six years into our marriage, I was the one who put motherhood back on the table, because I wanted to please him.

And I was curious. A child was the ultimate challenge.

Tom’s only condition was that my prison breaks must stop. As a mother, I couldn’t disappear for days on end. If I was to teach discipline, I must practise it.

We agreed that when the need became too strong, when the stresses and frustrations of ordinary life drove me to act out, I would limit myself to day trips and ensure I was back by nightfall. And I would tell him afterwards. Not in so many words, but with my mementos. He knows he can trust me. And so I never stray too far outside the lines.