I was married to a woman for six years who was clinically diagnosed with BPD. She divorced me two years ago. I feel what you are going through my friend.
First thing is to get into therapy once a week with a good therapist. It would be helpful to find a therapist who specializes in BPD because even though you don't have it, they will be very aware of what you went through.
Second, do you consider yourself a care-giver in relationships? Like, do you have all your sh*t together and take care of everything.... all the bills, planning, retirement stuff, cooking, cleaning, etc? Do you have a pattern in your relationships where you gravitate toward slightly immature women who don't have their sh*t together as much as you do? Looking back, I found I followed this pattern. It was almost like a parent/child dynamic. She relied on me to take care of all the many things she couldn't, while at the same time, resented me for it like a teenager resents the authority of a parent. You can't change people - if someone is immature and irresponsible, your strengths in this area will NOT rub off on them. They will not observe you and use that to improve themselves over time. Instead, they will take advantage of you for it, resent you for it, and start abusing you because of their steadily lowering level of interest in you. But they often won't actually leave you for it because they depend on you and because they have a fear of abandonment. Usually the only way to get a BPD person to abandon a relationship is to convince them that you are about to leave. Once they feel they have damaged the relationship beyond repair, they will bail on you before you bail on them. Abandonment is the worst possible thing for a person with BPD so by abandoning you before you can do it to them, they are saving themselves.
Please stay NC with her. No matter what! They are MASTER manipulators and will do anything to get back into your life and re-establish control. They are brilliant in how they attempt to do it. My ex tried to do it by reaching back out to me saying she wanted to share custody of our dog. It wasn't about the dog though - it was a way she could get back into my life and start asserting her control.... the control would have started out with disagreements in how often she gets to see the dog, or the logistics of pickup/dropoff etc, and would escalate from there. Knowing this, I didn't allow it. Bottom line, if she reaches out for ANY matter, do not respond at all. Even to say no. Just don't respond. No matter how much you know you are right and she is wrong, she WILL figure out a way to make you feel like you are wrong and get you to do what she wants.
Read "The Rational Male". It's a bit of a tough read, but is worth it. By far the best book I have read in years. You will learn the way things truly are and it will help you to correct your fantasy about what a relationship with a woman should be. That's not to say a relationship with a woman isn't and can't be wonderful, it just isn't what you think it is. You grow up forming this picture in your mind about what relationships should be like and it just isn't that way. Once you realize that, you stop craving it. Once you stop craving it, you stop ignoring red flags, putting women on pedestals, and allowing women to walk all over your boundaries and manipulate you. And once you reach this point, you will be forced to confront your internal issues that have caused you to seek relief or distraction through a relationship. It will be a journey. Read about "frame" to understand boundaries. It's in the book I suggested, and also in the DJ Bible.
Good luck and we are here for you through your journey.