Hi Millicat,
I am sorry for what brought you here, but hopefully you find comfort and support for finding this community.
I I don’t know how to be these things and not enable her drinking.
My situation is very different as is it is my mother who is uBPD. I'm not a T, and don't feel qualified to make suggestions. But I feel for you.

Something that helped me was reading "walking on Eggshells", and especially, "Loving someone with Borderline Personality Disorder" (by Shari Manning). The latter made the biggest difference for me, and is applicable to all relationships with BPD, not just family or romantic partner. I would really recommend it, as it offers strategies.