You're not powerless in this. You have 100% of the power to worry about YOURSELF, and to ignore her quacking.
That being said...I know you mentioned that you did it already?? but if she is threatening to harm herself, even if you don't believe her, call your version of 911 (emergency services) immediately.
You can't control her out of control drinking. Don't try!
I know though, it can feel like the most frustrating things to ever happen in your life...not being able to help her/get her to see the harm she's causing.
Try to find something you enjoy doing, that keeps your mind off her.