I am sorry, this is a tough spot to be in. My mom is an alcoholic, has been for over 60 years. I raised my brother, he is 11 years younger than I am. i am glad that I was there for him, he turned out A-ok.
Unfortunately there is nothing you can do to stop your mother, she is on a downward spiral. Have you talked to her about her drinking?
Keep posting, it will help.