Right, but it's not helpful for someone with BPD's recovery for the people in their life to just roll over and accept any and all abuse without proper boundaries. It can actually make them worse. So you did the right thing, for yourself, and for her, by not tolerating abusive behaviour.

I know it's hard. My mother almost certainly has either BPD or covert narcissism, and her behaviour is very similar to how you describe your ex, and I used to think I could help her heal by being the perfect daughter, but it doesn't work. You can never fill the void of insecurity in their heart, even if you are perfect. They have to fill the void themselves.

It's sad but they're adults with agency, not helpless puppets of their illness.