This whole thread is hard to read, my life has been very similar with my brother and parents. He has been an abusive alcoholic most of his adult life, and has also lived with them most of his adult life. He is now 49, and still lives with them. He never physically hurt them, but the emotional abuse/manipulation took a toll on their health. The blaming, the guilt, it was awful. I tried really hard to get them to see it, to help them get out of the situation. They would ask for help, then find a million reasons why they couldn't follow through with anything. They would get upset with me then for pushing things! They just wanted everyone to be quiet so my brother wouldn't get upset.
DreamsofSerenity is right on the money. I was powerless to do anything about their situation. They weren't going to change, and I was getting sick by being caught up in the chaos. I finally had to make a painful decision to step out of it. I had to detach completely from my brother, and stay away from their house. I see my parents when they come to my house, but I don't go to theirs. I focus on making them happy in my own way. When they're at my house I don't bring my brother up. I don't make suggestions etc. It's a sad situation, but it's keeping me out of the chaos. Now, if I ever saw my brother physically assault anyone...anyone....I would not hesitate to call the cops.
In "The Language of Letting Go" by Melody Beattie, the Jan 4th reading is about Separating from Family Issues. It's a beautiful reading, and helped me with my decision. AlAnon would be a huge help to you, I hope you find a meeting near you.