Alcohol isn’t always the reason someone is mean, nasty and condescending. Sometimes it’s just their personality and the alcohol heightens what already exists.
It’s silly to engage someone under the influence by trying to have a reasonable communication exchange. Even when she has not consumed any alcohol doesn’t mean she’s logically or rational…..you are still dealing with a alcohol saturated brain.
Drawing a line in the sand (boundary) only works if you don’t keep moving that line and re-drawing it.
Do some research on “detaching”.