I have a very good friend whose father died a few weeks ago. Although alcoholism wasn't directly his cause of death, all of the horrible physical ailments he had were definitely exacerbated by it.
The way he lived his life was horribly painful for his wife and daughter. In the end, they had to watch him waste away and care for him constantly. After the funeral was over and they had to really face what was left of his life...the feelings of abandonment, the financial disasters that had to be addressed, the anger and hurt...it was horribly difficult for my friend to grieve.
Two days after the funeral, she found herself screaming at the urn on her table that held his ashes. Screaming and crying...getting out all the anger that she couldn't express at her sick father over the past six months. It didn't make all of the lingering problems and frustrations disappear but it did help her take a little step in the grieving process.
Anger is a natural part of the grieving process. It's also a completely healthy way to feel when people make bad choices that affect us adversely. Don't be too hard on yourself for how you feel. As long as you don't get swallowed up in anger, it can be a very beneficial step in helping you move forward.
My condolences to you, your friends and his family. So very sad.