As the eldest daughter who became caretaker to my younger siblings, all three of whom have either BPD or traits, I can relate to a lot of the trials and tribulations of parents who have a BPD child.
What all three of them have complained to me about is my tendency to be an “overfunctioner” and they all get very triggered and start lashing out at me whenever I slip into overfunctioning. Perhaps this is what your daughter is reacting to. This article explains the concept:
https://www.psychologytoday.com/us/blog/everything-isnt-terrible/201910/are-you-overfunctionerI am currently on speaking terms with one brother who became verbally abusive about 5 years ago and would periodically re-enter my life only to cut me off within weeks in order to punish me for some perceived infraction. The last time he was on the brink of cutting me off I decided that I had had enough of the roller-coaster, and was fully prepared to walk away from the relationship, and I told him as much — not as an empty threat or attempt to manipulate — I was dead serious. I had also hung up the phone on him a few weeks prior when he started yelling at me, something which I had never done before. He seems to be taking me quite seriously and even though it has only been about 6 weeks, but he seems to now realize that I am no longer willing to tolerate verbally abusive behavior, and he has reigned his behavior in, and things have been civil between us for the first time in 5 years.
My sister, on the other hand has been giving me the silent treatment for the last 2 years and is showing no signs of letting up. She currently has an “ally” in my mother who has been working tirelessly at undermining (or perhaps, destroying is a more accurate word) my relationship with my sister, and I suspect that until they have a falling out, my sister and I will remain estranged, and recently I have been able to make peace with that.
If you give your daughter plenty of space there is a possibility that this “alliance” she is in with her dad could collapse, but it could take some time. What you could do in the meantime is try to strengthen any friendships you have, and maybe consider checking out some 12 Step meetings like Al-Anon. Wishing you all the best!