It's the end of the world as we know it, almost.

Bringing up small children is hard work. There's the loss of freedom, of sleep, of privacy, the strain on your relationship, which many marriages don't survive, the enormous expense and self-sacrifice, but then one day all the hassle and aggro melts away and there standing before you instead of this cute little high-maintenance kid, alternately charming and infuriating, is an adult: warm, witty, kind, fun to be with, a home-grown bezzie mate, someone you can ask to empty the dishwasher who might actually do it. Hooray! And then he leaves.

I think that's how lots of parents feel when their children go to university. The problem with modern parenting like ours: placing children centre stage instead of having them play supporting roles as they did when we were growing up in the 60s and 70s, is that when they go there's a real danger the show might fold. I received an email once, in response to something I wrote about motherhood and careers, from a woman who told me she was so depressed without a job to go to and all her children at university, she didn't want to get out of bed in the morning. I look back and realise that when my eldest son left home and I suddenly lost weight and couldn't sleep, it was because he took a small piece of my sanity with him. With another boy now gone, a third to go at some point, I can only hope to hold on to enough of it to continue to get up each day, but I'm not counting on anything.

You might say I have only myself to blame: having made raising these boys my raison d'être. If so, my husband is similarly culpable. He thinks nothing of going out in the middle of the night to track a son down, or chase after one who just left home without his glasses. While I busy myself dashing backwards and forwards to the shops to keep the house stocked with food and toiletries. And it is absorbing, making sure between us that they have all they need: books for school, doctor's and dentist's appointments, lifts to music lessons and sporting fixtures, but when they no longer need it, when they're no longer around, what then? 

When we took our first son to university we stayed in a hotel with him the night before. On our last morning together I was able to watch him sleeping in the moments before he stirred. It was poignant. How many times had I seen him sleep before? Countless. How many more would there be? Not so many. Of course a child's face is beautiful to his mother even when he's a fully grown man, but when sleeping it takes on an extra vulnerability that wipes the memory of all his faults and misdemeanours. In that moment, watching him, he was my angel. I wanted to throw my arms around his neck and weep into his shoulder because I was about to lose him to the world, and I knew it. But of course I didn't.

I thought I might have a similar moment before leaving Middle One at university this weekend, but a conspiracy of circumstances - including the city hosting a marathon next day - meant we didn't have a night together in a hotel after all. Instead, our leave-taking was a hurried and unsatisfactory affair in the street, in the dark, in the rain. I kept it together for the journey back to London, mostly because I was driving, then woke in the middle of the night wracked with sobs. His loss is keenly felt. He talked to me, a lot, and joked, sometimes we made the same play on words at the same time. But most of all, as with his elder brother, it's his music I will miss; music he played on his acoustic and electric guitar, on the piano, ukulele, mouth organ, music he listened to all the time in his room, music he played for me to listen to in the kitchen. Since he's been gone, and it's three whole days now, all that music has stopped.

Of course there's still one boy left: the quiet one, always in front of his computer with his headphones on. Sunday evening I tap his right shoulder. He looks round, pulls his headphones away from his ears. "Right," I say. "Just you now; you have my undivided attention."

"Jesus Christ," he says, snapping his headphones back on.

Love E x

@DOESNOTDOIT

P.S. "It is hard when your children leave," my mother says, when she rings to see how I am. "And the thing is, you never really get over it." Then she sends me flowers.