I'm so sorry for what you're going through. I'm glad you're finding much needed support. Fortunately, my situation isn't as dangerous (no drinking issues, etc), but I know what you mean about walking on eggshells just for the sake of keeping the peace. It gets old. Even though I know I shouldn't be doing it, I'm afraid of exactly what you described - that one day he's just going to choose to pack up and leave me behind so that he continue his self destructive behavior without my trying to change it.
For what it's worth, I think it's always harder to set your boundaries when you're trying to keep a family together. I don't have children myself, but a dear friend of mine went through many years in a horrible marriage because she wanted to keep her family together and thought things could change. I remember her entire family constantly telling her how bad her husband and his habits were and how she needed to kick him out and move on. Because she was getting that advice from all angles, I tried to be the friend that just listened and didn't judge or tell her what I thought she should do. I knew she'd reach her breaking point on her own terms and she did.
They got divorced, and she went through the painful process of healing. Over time, she started focusing on herself, developed a new outlook on life, got herself back in school, found a career she loves, and is an amazing mother. Her ex husband just continued to spiral out of control and is now in and out of jail. I know she used to wonder what might've been if he'd tried to turn himself around, but that is clearly not a path he was willing to take and she found a way to accept it for what it is. In turn, she and her son have done amazingly well for themselves once they were able to reach that acceptance.
Despite all of the advice you get from people close to your situation, the point at which you decide enough is enough is personal and only you know when you're there. It sounds to me like you're there. Sorry for being lengthy, I just wanted to share because your situation sounded similar to what my friend went through and I wanted to offer empathy and tell you that it can get better - much, much better. She is an inspiration to me and I'm sure you will be inspiration to others as you pick yourself up and regain your independence :)