My nine-year-old son Ino looked up at me with his big brown eyes and said: "This is so relaxing, Mum." We were only going to the shops, but because his twin Tom didn't have the same half-term as Ino and was at school, we were on our own for once. And because Tom is autistic, this made the trip to the shops very easy.
"Does Tom make you worried?" I asked.
"Yes," he said. "Happy, but worried. Now I'm just happy."
"You are not responsible for Tom, Ino, do you understand that?"
I say it to him over and over. He was born a worrier and I don't want the fact that his twin is disabled to ruin his life. But saying he is not responsible for Tom is only half-true. His parents won't last forever. He will probably be worrying about Tom all his life.
But at least he won't be on his own. He has a 12-year-old brother, Jack, who is very attentive and an eight-year-old sister Roise, who is gearing up for her First Communion right now and not keen to be messed about. I'm confident she'll get over that by the time she's 30.
But I will probably never be able to convince them that I can't treat him the same way I treat them. This morning, Tom broke my sunglasses in a protest against going to school and the others wanted me to insist he say sorry. But stand-offs don't work with autistic kids and I had to calm him down enough to get him on the bus.
I hope Tom won't always be as difficult as he is at the moment. He goes to a special school for kids with a range of disorders.
Twice this week we had to manhandle him onto the school bus. Then at 3pm I would hear banging on the front door and sometimes shouting in the letter box. When the door opened, Tom would throw his bag down the hall and start shouting: "I hate you because you sent me to school!" The whole afternoon would be a search for strategies to calm him down.
It's easy to say "You should just ignore him", but when he is out of control I can't be sure he won't hurt himself or one of his siblings, and I can be sure he won't damage the house.
Autism is a brain disorder which means the messages of the senses get confused. My beautiful boy, with his eyes of sapphire-blue and his perfect blonde bob, understands words literally. Combinations of words are a particular fascination. When I mentioned a "house fly" the other day it was quite clear he pictured a house with wings flying through the sky.
He's a mild case but, like most autistics, he has a range of other disabilities, too. In his case, it's dyslexia and learning difficulties.
My husband was once cycling home in the rain with a light with a loose battery which kept flicking on and off.
"I didn't know where I was going," he said. I suddenly thought, this is what Tom's life is like all the time."
You're thinking we're heroes and you're right. Nearly every parent of a disabled child is a hero. Humans are incredibly adaptable and parents are (usually) incredibly loving. There isn't a day I don't put my own troubles in perspective by thinking of parents who have to lift adult children out of bed every day, spoon-feed them and even change their nappies. And most of the time, they do it with love.
Tom has made me wonder at the power of love. He has made me more resigned to fate. He has made me nicer. Until you mess him about. Then I am murderous. I had to be pretty much held back once when a woman in a supermarket called Tom, who was having a tantrum, a "monster".
I haven't yet wanted to kill Tom, but there are times I wish he would go away and leave us in peace. Sitting at a coffee morning recently with other mothers of disabled children, one mother of two autistic kids admitted she'd tried to throw them down the stairs. None of us batted an eyelid.
Most of the time, I love Tom to bits. But I don't know how I'd cope without his father. I think the disability has brought us closer, because he loves Tom as much as I do. While disabilities may make strong marriages stronger, they can make weak ones weaker.
I won't be able to keep the family together for Tom, and I won't try. His brothers and sisters will go off and make their own lives and their own families. That's going to be very distressing for Tom, because his whole security is in his family, and also he will have a sense of being left behind. But I hope he hangs on to both parents as long as possible.
We won't be enough for him, though, and I'm beginning to imagine some kind of communal life for us with other disabled children and perhaps their families. Tom won't be able to work for pay, but he will be a strong and willing young man and he loves working with animals, gardening and cooking.
There won't be cruises or wine courses for myself and my husband, certainly, but when you think about it that kind of retirement is pretty selfish.
He's changed everything about our family, then, but the biggest lesson he's taught us is not to fear change.