Thank you for your kind responses. It helps put things in perspective for me. The final recent closing message(s) from the pwBPD sound coherent and well written. She is definitely smart. To the observer they don’t read like she is a nutter. But they sadly describe a person and actions of that person ( me) which I’m not. And a now hatred of me that is evil, scary evil, and firm in its finality..It’s like they have made up a character. A persona and fit me to it. One they deep down hated from their past. Maybe it is a persona around one of the men that abused her or neglected her as a child.

? I often wondered if that could happen. Certainly arguing and defending against shadows , nonsense and untruths was a big part of my role. It’s funny tho how you know they actually love you and you represent everything they have ever wanted. But then do their best to ruin it, destroy it. With no ability to truly self reflect. That concept is anathema to them. A leading psychiatrist and bpd specialist told me years ago , back in the 90s, that borderline really meant they were on the borderline of madness …in and out of sanity to madness and back again.. that description stuck with me. Maybe the studies have progressed that definition since but it sure made sense to me then and does now too. Sadly I have had definitely two or maybe three pw BPD in my life. It’s so good to read others have had the same nightmare and I’m not going mad. The similarities are frightening. And remarkable.
My BPD mother was intelligent.
It was sad to wonder if she ever actually knew me or that what she knew about me was filtered through her projections and emotions. So this isn't exclusive to a romantic relationship - it involved other family members. Ironically, BPD seems to affect the closest relationships the most- as they involve the most emotions. That is one reason why it feels so crazy making when people they aren't as close to don't experience it.
It is possible that prior abuse is a factor with BPD. Not all the time but it can be. I don't have any actual evidence but I have wondered if my BPD mother was abused by someone and if that experienced shaped the projections. Sometimes there's no event like that and BPD develops in a person who is emotionally or genetically vulnerable- and is sensitive to lesser situations where another person wouldn't be. Sometimes it's not possible to know why.
I have had the experience of helpful behaviors being misinterpreted. In her elder years, we kids would plan visits with the intention of helping BPD mother. We would spend the whole time doing errands, helping her with tasks, as one would think adult children would do for an elderly parent. Yet, she would find something we did or didn't do, or did incorrectly and get upset about it.
You are hurting and trying to make some sense out of the situation and wondering how could someone who supposedly loved you, and who you loved, act like this? You gave this your best effort, and being human, you aren't perfect. Nobody is, and if someone has a filter of projections, nobody can be perfect enough. It is sad that your ex could not see you as you are instead of through her emotional filter. You are correct in that you didn't create that filter and you can not change it.
I hope knowing this helps you to come to some peace over what happened.