Damn, I am truly saddened to hear about this.
I have a similar relationship with my brothers so I can only imagine how you must be feeling.
Do you happen to know if the party driving the truck is ok? It would be even more of a terrible loss if the other driver didn't make it as well.
At any rate, I will be throwing a few coors down here in a few! Best wishes for you, your nephew, and the rest of your family.