the rest of the post was supposed to be -- maybe if you were to talk with someone who specializes in dealing with people who are in grief, it will help you also. Good luck, dear. It is possible to feel more like yourself, even though you don't forget what happened.
I am very sorry for your loss. The answer is that he died because his particular liver could not take it. It really doesn't matter if other people drink heavily all their lives and don't die early, I am so sorry but his own particular liver was not built for what happened to it. Either this was caused by (it certainly was not helped by), the fact that he was a heavy drinker; maybe he also had some congenital weakness of the liver that made it more susceptible to problems. Also, other things that a heavy drinker might do can cause liver damage. (For example, maybe he also had hepatitis.) Again, I'm sorry. I recently saw a grief counselor, and it helped a lot to have someone to talk to.