You poor girl
My father left home when I was five, and my mother took to drinking. I grew up with a drunk mother, and it isn't something I would wish on anybody.
She died when I was 23 and she was 45, and the impact of my upbringing (and her sad and lonely death) has impacted hugely on my life and aspirations.
It is possible to survive, but she has to give up immediately. Beyond that, and I'm being brutally honest here, you must prepare yourself for her death. And it may happen very quickly.
Unfortunately, there is very little that you can do for her unless she wishes to do it for herself. This, I am sure, makes you feel emotionally washed out ... that your own mother would kill herself when she has you. Do you mean nothing to her? Does she not love you? Was I/am I a crap kid?
Yes, you are helpless and useless in the face of it. No one subscribed to this particular form of misery, least of all you. My only, and very good advice to you at this juncture is this:
Take a deep breath, remember that you are loved, and that none of this is your fault. Talk to her, on your knees if you have to, and try to get her to AA. Try this for a month and no more. Tell her that you will go with her. If she has been brain damaged by alcohol, AA has an evangelism that might appeal to her at this stage.
If she won't go, at least you can't beat yourself up over it. And it's really important that you don't suffer guilt. Believe me, I speak from horrible experience