Hello chobers,
It is hard to let go of hope, especially as you get older. I totally understand that feeling of still being attached, I still feel it at times 14+ months after being introduced to the trashcan.
It must have been exceptionally hard to hear from her that she suffers from BPD after 2 years of being with her. I get why you would feel sucker punched. I assume since she told you that means she has received an official diagnosis? Did your research on BPD give you any clarity with regard to issues that were present in your relationship?
Given her "no" with regard to getting help, her age and the nature of the disorder your conclusion that she will never change is almost certainly a correct one.
If you feel comfortable sharing more of your story it will help. We are here to help you through this.