My SO was diagnosed with BPD a long time ago and never took it seriously, but she's told me about it. We have a difficult relationship, full stop. I keep on trying because I think that I understand what is going on. But, I cannot lie, this is very hard for me to continue and right now I'm not wearing my wedding ring since she took hers off fist and gave it back to me. I'm actually writing this locked in my office because she's acting like a child again (screaming, pounding on my door, throwing things) after insisting that my tone wasn't convincing enough over 12 hours ago, when I told her that I married the right person. (EDIT: Just re-read that and, my god. I'm not without self awareness, but this sounds nuts.) 

I believe she has the discouraged subtype of BPD that occasionally manifests with petulant/self-destructive traits. In practice, this means my wife of nearly three years (six total together, going on seven) often refuses to believe that I love her. To make matters worse, she gets very angry and defensive when I contradict her about my thoughts and emotions, and insists that my tone is the truth of the matter, allowing her to assign whatever malintent she has in her head to me, discounting my actual words and deeds entirely. Try as I might to keep the frustration out of my voice, this becomes nearly impossible when she's acting like a child lashing out at a mean parent, especially when she's breaking things, or pounding on a door, or slamming doors in my face, or calling me awful names (which I'm sure the neighbors can hear). 

How am I supposed to talk to her about getting treatment when this is her reaction? Even mentioning BPD to her (did that once, still regret it) is counter productive, and we're going on two and a half years since she promised me she would seek treatment with a professional councilor. Still hasn't happened. 

Whenever I talk to her about that, and how disappointed I am that she won't fulfill her promise to me, she makes it about me and asks why I cannot hire a marriage councilor to talk out my bad behavior in the same setting with her. This always blows my mind... It's like she needs to always draw an equivalency or refocus our conversations to make them about me and how horrible I am... She cannot accept that she's the cause of 99% of our conflict, and I am sadly at a loss on what to do next. Oh, and FWIW, I cannot hire a marriage councilor because she hasn't had a job in years and her client work is very spotty at best, so I go broke every month supporting her.  

You all seem to have some insight. Please help? 