Recently someone asked me how to prepare for the loss of a child you know isn't going to survive very long. Short answer: it can't be done.
You can intellectualize things: you know the science, you know what the doctors are telling you, you can see what's happening. You mentally prepare yourself, or you try to. You think you understand.
But you don't.
It's like standing on the edge of a cliff. You know there's a danger at the end and you feel a little adrenaline rush as you look over the edge, imagining what it would be like to fall. You know falling would be a terrifying thing and you think you understand that feeling.
And then you fall off and even before you hit the bottom you know that you had no idea what it would feel like.
That's it really, it's the way it FEELS. All the intellectual processing and understanding and mental preparation in the world doesn't help with the way it feels. and it doesn't feel good. It's like a long slow fall off a cliff, falling falling and not knowing when you will hit bottom or how much that will hurt.
There are good times, of course. Little things jog your memory and you laugh remembering all the amazing things. Sometimes you laugh really really hard. Sometimes it's just a quiet smile. Those are lovely moments, but they are bittersweet, always bittersweet.
All anyone can do is feel it. And remember the child. You can remember the child publicly or privately or both. That's what will keep that child alive for you. That's how their life will count, by being remembered.
Just remember, because the sweet is worth the bitter.