It sounds to me like you have reached the point where you realize you are getting nothing out of this relationship but perhaps are hanging in there and making an effort simply because he is your brother? I cannot say what is right for YOU, only you can do that. You may want to give Al-Anon a try. Also, there should be plenty of books at your local library on Alcoholism.
I personally had to cut all communication with my youngest brother, who was what I thought was my best friend for most of my life, because of the sickness, chaos, and pain he brought me. I have never regretted that decision. I found my peace that way. I realized that I held onto him, kept him in my life despite all the problems he created, because I had an idea of what life is supposed to look like. I thought I knew what brothers and sisters do. It was like some kind of dream that existed only in my mind, and never in reality.