I think professional help would be required for her to feel better
Obviously, after all these years of trying, you can't lead her toward recovery. She sees too much of a hurdle to truly listen to you due to the immense emotional baggage of the past in your close relationship. An emotionally uninvolved professional or respected expert is typically the best hope, but there are so many ways she can sabotage that too.
She hasn't been diagnosed, not even close. Nor do I know if she really has bpd.
She can appear really fine one second, joking with the kids, being a really charming mom, the next minute she wants me to talk about some betrayal. Whenever she hasn't touched a topic for some time, she has to review it again from her current perspective.
Many of our loved ones in our lives were never diagnosed. My ex sure wasn't, she refused any recommendations, even when our child's pediatrician tried.
My ex too could flip from one extreme to the other in a flash. That is typical BPD behavior. So... don't fret over a diagnostic label. You've been here for years and we've always agreed that BPD was a strong possibility. Deal with what patterns you see.