I made the mistake of trying couples' therapy
I wanted things to work out after a short break-up & didn't know how harmful it can be when dealing with a pwBPD, so I decided to try it. We went through two therapists fairly quickly, but the third stuck around & it's honestly been one of the most confidence-destroying things that I've dealt with apart from being bullied in junior high.
For instance, last week my pwBPD snapped at me because I was "being really fucking annoying." All I did was ask a couple idle questions about something she said. The topic was about as low-stakes as it gets, so I was fine with dropping it but I did ask that she not talk to me that way. She doubled down. Hours of silence between us before she finally said "sorry." I brought it up in therapy later that morning, and... the therapist said that I was the problem, and my refusal to admit that I had done anything to warrant that response was taken as hostility.
I know this term gets overused, but that left me feeling fucking gaslit. It seriously makes me feel like I'm losing my mind.