That sounds so hard. I'm glad you've reached out for some help. It does help to step back and say, "Huh, if she's determined to drink there's really nothing I can do to stop her." It just gets the pressure off you a bit.
I think it also helps to have your experience reflected here. She will most definitely attack you, in whatever way she can, if she sees you as an obstacle to a drink. It's just what happens. Not your fault at all.