It's okay to be angry. You are going through the stages of grief. Angry that he died, angry that all the dreams you had are now truly gone. So much we want to believe when we are with the addict that one day they really will change and provide for us the life I truly believe they want to, but for whatever reason, cannot. What I will say is that none of this is because he didn't want it bad enough with you. Addicts and alcoholics are very, very sick people. I do believe that in their heart they want to be better and they aren't all not getting help because they "don't want it bad enough". They are sick, and sometimes they cannot reach that point of getting well. It has nothing to do with him wanting to get better enough for you.
You are angry that the dreams with him are gone when we always had a tiny speck that they would fulfill.
As for not understanding what killed him, I don't know nor does anyone else really until the autopsy is back. What I will say though is that the body can only take so much. If he was "able" to drink much more and survive, sooner or later the body just stops working when abused long enough. Much like people. You can only take so much.
I am thinking of you lots as I lived with the fear of my ex being found dead in a hotel. He did the same things, drank weeks on end with no shower or food. Miraculously he survived each episode, but that's just for now as far as I know. The best you can do is heal with support and keep posting here. This forum is a lifesaver. Hope you can find some grief counseling or alanon meetings. Lots of love to you