Hi Bspace,
Welcome

Sorry that things have been so difficult in your relationship. I'm glad you found us. We have a lot of great tools available for helping those of us in a BPD relationship learn new ways of communiating with our pwBPD. TO get you started here is a lesson on
The Dos and DOn'ts of a BPD Relationship She's getting sick of my excuses for her father and I am too. Help... .
I don't have children but I can imagine how hard it would be to be torn between protecting them and letting them understand what is going on. I would suggest that one thing to help her is to not make excuses for your H anymore. Don't complain about him to her, but something as simple as "Your dad is drunk. He drinks too much too often." could just open the space for her to feel like she has some understanding of what is going on. She knows that dad is drinking. She knows that he acts a certain way after drinking and it may be causing her confusion to hear his behavior explained away or excused.