In 1952, my parents lost a daughter at 1 yr age to an accident, had 2 small boys to care for, more afterwards (inc. me). From what I understood from them, there was nothing for it but to focus on trying to help the rest of the family cope, and focussing on living in the here and now, because you never know what tomorrow might yet bring. Dad lived it too, I remember 20 yrs later him allowing us younger kids, even encouraging us to enjoy any little thing that dragged us back into life after mom died suddenly - in the middle of her life, and our childhoods. I have never lost a child, but I’ve had a couple deaths that I found (find) hard, esp. one that came out of nowhere, as accidents do.
A death is a full body blow; it shakes you absolutely to the core. And it sounds like your loss just had a dozen additional heartbreaking details making it exceptionally hard to disentagle from your thoughts. You just gotta let in a little sunshine or warmth whenever you get a chance. Try to live in these moments so you can enjoy anything on offer, regardless of what the big picture looks like. You live life day to day as best you can, collecting as many pleasing moments as possible, and let the years go by. I don’t think we ever feel any better about these losses, we just get more used to the pain, more skilled at distracting our thoughts, less shocked by our occasional breakdowns, and definetly less shocked by the news of the loss itself - amazing how many yrs it takes for the shock to lessen, but getting accustomed to the idea that this did happen is a small help that definetly does come with time.
You have made it this far and it’s a huge accomplishment. You write about your other children and your wife, so you are considering them as much as you can too. Give yourself full credit for what you can manage. The vast majority of us will never be up against anything so challenging, certainly nothing so long-term a challenge. I’m so sorry you are all going through this and I hope things get brighter for you. Fight the good fight and try to focus on helping others in the family cope, doing so might bring your own mind at least as much peace and comfort as you are able to offer the other person. Even if it doesn't help you, if you only made at the other person feel better, that’s still a win. You don’t need to know what to say, just listen. If no one talks, just being there is good too.
We’re pulling for you.