Thanks to all that replied, it really does help.
With regards to the last part about having to share a room, we live in an apartment- there really isn't any space for another person to live. We can't afford for me to live somewhere else, though honestly, I love living at home, except for my brother's drinking. I feel like the only thing that I can do is as Alice said, do my best to detach myself mentally. That probably makes it more difficult but I can take it, and although I am very hesitant, I should check out a few Alanon meetings- and at the very least continue reading their literature. I guess I have to wait a while until I can physically seperate myself, but it's comforting to know that detaching mentally also works. Thanks again for the support.