TLDR: My mother has been diagnosed with BPD, but doesn't want to accept it while also exhibiting way too many signs of BPD. How did you come to terms with your diagnosis?

I'm a 28m, and often have long conversations with my mother in an attempt to help her through painful experiences. She was an abuse victim at the hands of her parents, alcoholic father who was abusive, and an absentee mother who disassociated from it all. 

This had affected my relationship with my mother since I was a kid. Ever since I moved out at 16, we've done a lot of work on our relationship and we're in a good place. We talk for an hour or two every week over the phone, and I'll always love my mother for the stuff she did for me as a struggling teen. 

One thing I'm having a hard time wrapping my head around is the way she navigates conflict, relationships, and how that all ties into my interactions with her. She fits the BPD criteria almost to a T, and was even diagnosed by a doctor for it, logically its the only way I can rationalize her actions in my head. However, she refuses to accept the diagnosis, and has since shopped doctors till she got the diagnosis she wanted, she was being medicated for Bipolar until suddenly another doctor determined she never had Bipolar. I just don't trust what these doctors are saying, considering it's a new one every 3-4 months. I've done research on a lot of what she's been diagnosed as, BPD is the one that lines up the most. 

On any given day, she exhibits the following:

*Severely impulsive with her decisions, will completely rearrange her plans when something doesn't go as planned, minor or major. 
*Mood swings, usually triggered when things don't go as planned
*Unstable relationships, is currently contemplating divorce after 7 years while having a husband who goes the extra mile to please her, has completely cut all ties with every single family member except for me
* Is relentless in diagnosing others as Narcissists, including her husband who's been diagnosed with Dissociative Disorder and is not a narcissist
* In constant fear of me abandoning her, asking me a lot to just "tell her" what the issue is instead of leaving like she did with her parents, even if there's absolutely nothing wrong
*Doesn't hold friendships for very long, completely loses touch with friends after 4-5 years 

At this point, I think the only way she can truly repair her relationship with her husband is having an open mind, realizing her diagnosis, and developing coping mechanisms to help each other with their respective diagnosis. But every single time we even approach the subject of couples therapy and opening up, she's convinced it won't work because her husband is a "narcissist" and that it won't work. She, half heartedly agreed last night over the phone to go, but I'm not sure she'll follow through. 

I think what she's scared of is the diagnosis itself, like it somehow means she's an inferior human being for being diagnosed with it. To me, it's the only thing holding her back from making some serious change to her mental health, and possibly forgiving or forgetting her parents for what they've done so she can move on her with life. But she doesn't want to let go of those emotions, as we talk about EVERY SINGLE TIME I call her, for the last 4-5 years. I love that women to death and will do anything for her, but she makes it very difficult sometimes. 

Redditors, how did you come to terms with your diagnosis? I feel like it's WAY easier said than done, but is the only road block at the moment.