Readysteady, as you read in my post, my experience is somewhat similar in dealing with my sister. I don't know anything about how your brother got to this point, only what you informed in your post. I understand the mixed feelings, and the sense of responsibility on your shoulders. But if there's one thing I learned in all these years having to deal with a hardcore alcoholic is that she is not my responsibity, period. I won't fight her to get her treatment, rehab, nothing. I'm waay over that phase. And even though I don't live with her, she still sucks the life out of me and everyone else.
Like I said, I don't know any details of your situation, but your brother sounds like he will destroy himself and everyone around him in the process - you for sure.
I'm sorry if I don't have any comforting words, my experience is harsh, and my advice to people dealing with alcoholics is always this: run away as soon as you can.
Take care. PM me if you want to talk.
B.