Did I ever tell you about the time I nearly died? I was young, at that age where all my memories blend into one entity, never knowing where one memory ends and another begins. I was in the living room watching cartoons, eating Maltesers. I inhaled one by accident and it stuck in my throat. A perfect time-pausing fear overcame me and I sat frozen in place. I couldn’t move, couldn’t breathe, couldn’t think. I just sat there, terrified to move. I don’t know how long I sat there for before running into the hallway, thirty seconds maybe, up to a minute, but it felt like a lifetime.

My mum was in the kitchen with her back to me. I couldn’t scream so I just stood there, waving my arms. She never turned around. So I stamped my feet, jumped up and down, then she turned, assuming I was messing about and trying to annoy her. I think she was about to shout at me but she saw the blue of my lips and ran over, turned me around and started trying to dislodge the sweet.

Then the fear left me, replaced instead by this creeping darkness coming in from the corners of my vision. To this day I still can’t quite describe it adequately, but I will try. The darkness had a form, not like a shadow, but 3-dimensionality. It came from behind my then started to cover the carpet beneath my feet then creep up the walls and down the hallway. I was not afraid of it. It was so warm, so inviting, like silk wrapped around your shoulders, the velvety hug of a soulmate after you’ve suffered a devastating loss. The darkness drew me in when I had no fight left in me. I was ready.

The Malteser flew out of my mouth and bounced down the hallway. The darkness fled immediately, the fear rushing back in and I ran to the toilet and threw up, crying like I’d lost everything. I’ve heard people say that depression feels like you’ve lost someone, then realising it is yourself. That feels about right, I think. I still think of that darkness now and again, when the nights are cold and I’m by myself. I think of all the people terrified of dying, but they don’t know. You are embraced by the universe, as if time itself will mourn your passing. It feels good.
This is cool.

"She never turned around" is a false statement corrected shortly. I'd just alter it to something along the lines of "ignored me" or something of the ilk.

"To this day..." adds unnecessary words when you explain things well after.

Your description of the creeping of death as a silky entity is great. Full stop. Stop again. Great.

I'd lose most of that final paragraph.

The biggest weakness here is the conversational tone. Removing that gives the piece immediacy, which fits with the feeling of choking. Choking is a sudden action, and that's what you need here. Let the structure fall in line with the scene.
I am a fake mountain.