In the beginning I was just a dad who fell over a bit and then couldn’t drive the car. Then we had a name for what was happening to me: motor neurone disease. The rest of my physical decline has taken two years and I now write with a camera attached to a computer, which tracks reflections from my pupils. I can use the same device to talk with my synthetic voice. It’s obviously slower to use, and has trained me to get to the point, in much the same way that dying has.

In the room next door, as I write, I can hear Jimmy, my two-year-old son, offering to take passengers on a bus ride to various destinations. It’s half-term and Tom, my seven-year-old, has wandered out into the garden. He’s smiling, looking back at the house, as he points out a squirrel to someone standing inside. There’s adult laughter, too. I can hear Gill, my wife, talking with one of my carers.

I’m in an adjacent downstairs bedroom, suspended in a sling that hangs from the ceiling hoist. It’s positioned over a bedpan, and my floppy neck is wedged upright between a pillow and a piece of foam. I usually stay here for a while because it also has a view of the garden. It’s gusty and leaves are twirling down from an ash tree.

I realise I’ve been saying goodbye to my family for two years. Always imagining this version of myself, without a voice or moving parts. But now I’m here, I can see that we’re all just interested in the same thing: how anxious all these squirrels are as they bury their treasure in the turf. How they keep looking back over their shoulders. And how life just carries on, until it doesn’t.

There was a moment halfway through my decline when Tom needed to check whether he would die one day. He was wrapped in a blanket on my lap as I confirmed its inevitability. He sobbed and I pulled the sides of the blanket in around him. After a few moments his tears came to an end, and five minutes later he was upside down on the sofa giggling at his toes.

Children walk past spiders’ webs all the time and see little things dying. Death is all around them; they know this better than their parents, who have often forgotten. I know I had. But children haven’t reached this stage yet. Death and dying can be known. It doesn’t stop them laughing at a fart or making an empty crisp packet go pop.

Jimmy was at my bedside a few mornings ago dispensing imaginary ice-cream. I was staring upwards, and I could hear him low down to my right. I opened and closed my mouth to show that I was eating some of the “[va]nilla” on offer but, silent and motionless, I don’t know if he noticed, and then I heard him padding away into the next room.

I see three people moving and turning together – and it’s no longer breaking my heart

I can’t be active in the life of my children. I have to see what the day brings. There was the moment last week when Tom rested his cheek into my upper arm, gently twisted the top of his head upwards against my flesh like a nestling cat, then twirled away. It was a moment that must have lasted five seconds at most but I kept it with me – held on to it – for days, as if I wasn’t just making contact, but taking an imprint.

I owe these moments to materials that are both plastic and hollow. To an expanding network of tubing crisscrossing my body: transparent blues and yellows, concertinaed or smooth. The largest gauge of tubing has the central importance of the eastbound M4 heading into London. This is the one swooshing air and oxygen into my lungs, but there are other tiny subcutaneous tubes more like narrow Cornish lanes, trickling a minuscule palliative cocktail just under the skin of my bicep. The other key thoroughfare is the one delivering sticky beige nutrition through a macaroni-sized tube running directly into my abdomen.

Tubes are now a way of life and, with so many doctors and nurses coming and going, there’s plenty of spare tubing lying around. This place is like a fisherman’s cottage but with coils of plastic everywhere – in wicker baskets or hanging from hooks. A lot of it ends up in the bath with my two boys. Or it becomes part of Jimmy’s marching trumpet band.

When I was diagnosed, my heart broke in different ways, but some of those feelings have softened. It was always the tiny pieces of future that hurt. I’d imagine Gill and Tom and Jimmy unloading shopping, or just being listless together on a Sunday.

But I’m very still with this disease now: I’m an observer, sensing lives happening in other rooms. I hear bottles and cans rattling in plastic bags. I see the rain at three o’clock on a Sunday. All this detail goes by or around me and I see it working. I see three people moving and turning together – and it’s no longer breaking my heart. It’s just sad and comforting. I didn’t expect the end of my life to feel like the future.

Hammond and his family at home last month. Photograph: Julian Anderson/The Guardian

I see and hear my family clowning around and I want so much to be in there with them – teaching my children to brush their teeth in the style of a camel. Instead I’m unnaturally still – observing the way their bodies move to express or receive humour. The way a back curves, or a head is thrown back. Watching hands thrust out wide, or even the opposite of such movements. All the infinite expressions. But I’m not clowning around any more; I just see it going on – how ornate it is, how beautiful.

Other losses are simpler and more incremental. Sometimes they are nothing more than adaptation and sometimes, like the loss of my voice, they are devastating. I lost my swallow very quickly. There was a three-week period when Gill made sure I had lots of really nice soups, and that was it. Food was a thing of the past. I’ve never got over that loss.

I’m fortunate that my ventilator filters out the aroma of most foods, replacing them with a smell like the inside of a plastic bucket. Occasionally smells get through, like roast lamb or the mist that comes from Tom peeling an orange, but mostly I’m assailed by food memories. The most recent is of the yellow Styrofoam containing takeaway from a Lebanese restaurant. Other food memories are more permanent and catastrophic, and these are all the foods I ever made or shared with my young family.

When the boys are in bed, Gill climbs up on to my hospital bed and sometimes falls asleep. It can feel like I’ve been waiting the whole day for this moment. Watching Gill asleep always feels like such peace to me, and some of this article would have been written with Gill by my side in that way.

It’s really hard to cry when you rely on a mask for air. I use a mask that’s attached to my nose, so when I cry my mouth stretches wide open and all the valuable air gusts out, like a badly insulated letter box. And the camera I use to communicate can’t track the progress of my pupils, so crying is a form of incapacitation. It’s so much easier for Gill, who can stretch out on the bed and sob without any of these secondary difficulties. It’s not that we’re always crying together. It just happens sometimes. Recently Gill’s been reading to me from old travel diaries, written in the days before we had children. Stories of mountains and recklessness on motorbikes, other countries. The past feels so luxurious.

But now it’s the present. It’s all been leading up to this. Sad but no longer broken. Here with Gill. It’s a magical kind of sadness, saying goodbye. A bit like preparing to travel again, but no longer together.

• A Short History Of Falling: Everything I Observed About Love Whilst Dying, by Joe Hammond, is published by 4th Estate.

• Comments on this piece are premoderated to ensure discussion remains on topics raised by the writer. Please be aware there may be a short delay in comments appearing on the site.

If you would like your comment on this piece to be considered for Weekend magazine’s letters page, please email weekend@theguardian.com, including your name and address (not for publication).