Pete, I am very sorry you and your family are going through this. My mother died unexpectedly over a decade ago and that was, and still is hard for me to deal with. I hesitated posting anything here but since this happened in my mother's family, and I grew up with it too, I thought I'd pass it along.
My uncle, (mother's brother) died in a single car crash in my home town of Bradenton two years before I was born. He was one of three children of my grandparents and the only boy. He was 16 and on his way home from high school baseball practice with two other boys. One of which would become my uncle a handful of years later when he married my aunt.
My mother's family, now down to four, were of course devastated. My grandfather blamed God and basically washed his hands of church for the rest of his life. It wasn't until the year he died that he told my Mom he believed in God as she wanted him to go to heaven and had been talking to him about it. My grandmother, the picture-perfect Southern lady, was bed-ridden and basically didn't leave her house for half-a-year. My aunt, the youngest, was stuck in a grieving home trying to make some sense of it all and just survive. My father, even to this day, says that it was some of the strongest grief he's ever experienced. (And his grandfather too was killed in a car accident.)
Growing up, I was the first grandchild and boy did my grandparents spoil me! I was aware of my deceased uncle but hardly anyone ever spoke of him and there were no photographs of him anywhere. That was the case until after my grandfather died in 2000. Only then was my grandmother able to put some up. Apparently as a little boy, I told my grandmother that I was her son come back to her. To this day, I wonder about that and why I said it. I did play a lot with his old toys, which were pretty cool.
It wasn't until I was an adult that my grandmother told me what made her feel better and got her out of the house after the accident. She had walked into the bathroom that my uncle used and she said there he was. He told her that he was fine and for her not to worry. I don't remember what else she said, but it was that encounter that enabled her to continue on with life and I have never doubted what she saw. My grandmother went back to church after that for the rest of her life albeit without my grandfather.
One other experience. When I was a teen and living in the Los Angeles area, my Mom forced me to go to role play at a local church. This was done by a pastor who was a leading authority on families using role playing exercises to work through problems. Usually by turning the roles around so that kids would have to see and deal with situations from a parent's/adult's perspective. I had sat there stone-faced for many a meeting. Still working through anger about my mother's multiple marriages, etc. The one thing that broke through to me, and got me crying in that room full of adults, was seeing my Mom cry after working through a role playing exercise that dealt with the death of her brother all those years ago. That was an extremely strong moment and I still get goosebumps as I type about it. That was the first time we had even really talked about her brother.
Pete, a big hug to you. I have a lifetime of dealing with this family tragedy -- and its fall out. My hope is that something I wrote here can help in some way.
Gene