I don't doubt that they contributed to your BPD. My understanding of it, based on having worked in mental health (not as a practitioner, but on the front lines, and having been close with many practitioners), and based on having had a best friend/roommate who had all the classic symptoms and maladaptive coping skills of BPD, is that it is PTSD based on repeated violations/negations of personal boundaries during the developmental years. I don't have BPD, but I do have PTSD, and I had to work out a lot of my own maladaptive coping skills. I have a lot of empathy for those who struggle with BPD, I've experienced what it can do to relationships as well as witnessed what it can do to the one literally suffering from it.
Some of your story resonates with my own experiences with my parents. My mom was physically and verbally abusive to me, and hugely controlling. When I moved out of state for better opportunities, she found all kinds of excuses for them to never come visit me in over a decade, in order to validate her personal grudge over it. It's possible you'll never be able to make sense of how you've been treated because it doesn't make rational sense. And even if you can figure it out, if someone isn't willing to look at themselves or to make changes, they won't. I've lived through that my entire life and it's utterly frustrating. I was even told by my mother when I was a teen and a child psychologist tried to intervene, "We're not going to change, you are," and my parents pulled me out of the therapy that supported me, and the physical abuse and craziness continued. Over the years, I bent some, but I never genuinely changed. I never accepted the family narrative that "It wasn't that bad" and, from my father, to "just get over it." When I finally had a diagnosis for lifelong back pain that indicated a severe physical trauma, and demanded my parents take responsibility and help me, my mother said in an email that they were tired of the "blame games," wished me well, said they'd always love me, and said goodbye from her, my dad, and their pets for fuck's sake. Then a couple of years later, I had to email her and shut her down when I lurked her Facebook page and saw that her profile photo was of her and I together at an event over twenty years ago, and in comments she was saying that she and I are still thankful to the person who threw the event. Just no.
I totally agree with the comment that sometimes no contact is best. It took me decades to get to that point, in phases. It's hard to do. It's hard to stop retuning to the slot machine of hope that never pays out the jackpot. I still love my parents, but the insanity is insurmountable as long as they're not willing to do the work to overcome it. They are not at all willing to change. Sometimes it's like they're in a cult, their ways and their beliefs are that twisted. To the outside world they are great people, successful in life, and very common-sense.
Anyhow, in abuse situations, someone has to be the scapegoat to justify the underlying hidden narratives of abuse and mistreatment. Those who buy into the narratives can't and/or won't see the victim as they really are, because then the narrative, the glue that holds the abusive family structure together, will fall apart. Those who most strongly buy into it will fall apart because they don't have the inner strength, let alone the will, to face themselves, their own root traumas, and the awfulness of the actions they perpetrated against another. In these situations, someone always has to lose, that is, the scapegoat, but really, everyone loses.
If you or anyone who reads this is seeking helpful recovery resources, after decades of therapy and self-work, these resources helped me the most, as well as The Dialectical Behavioral Therapy Skills Workbook:
https://sanctioned-suicide.net/threads/resources-for-learning-boundaries.30500/
Edit: And yeah, the ignorance you mentioned. Racism, judgmental, faith in abusive governmental leaders and power structures.
