I have experience with alcoholics in the family and haven't drank more than a handful of drinks in the last 5 years, because I don't want to go down that road, but the things you need to ask yourself are: Are you prepared to have her never changed and eventually drink herself to death? Are you prepared for her behavior to get even worse over the years towards you and herself? Are you prepared for the drinking associated health complications, she won't be able to function as an adult for her last 5-10 years. Are you prepared to deal with potential DUIs, job losses, and other alcohol related complications? Are you prepared to give up your life to deal with her situation?
If the answer is no, you need to think about your future with her. You can't help her through this one.