Hi Dad.
I read through your previous posts. Your situation has a lot of moving parts. So I might need to stress that I'm responding to this specific question only, and basing it off my own experiences.
My question is can a pwBPD regain trust after something like this
People generally don't like being told something is wrong with them, especially if there's a stigma attached to it.
I've tried talking to my wife about BPD. It never ended well. When she's bad, I have never even been able to point out specific symptoms without her getting angry. Mostly because at that time, she's already frustrated/anxious and wants to be heard/understood; not told she's to blame for anything. The typical response... ."Yeah, it's always my fault!"
If I stop rocking the boat and wait, she will normally apologize for blowing up. It could be a few hours or a few days. But I noticed enough of a pattern where I'm confident I can just swallow her surreal and/or accusatory comments and that it will eventually correct itself.
Her dad died almost exactly a year ago, and things have been really rough since. At some point, I straight-up told her that if she wouldn't talk to me about her issues, then I was leaving permanently. I yelled it (bad idea), but I meant it (truthfully).
I found a book sitting on my computer a couple weeks later. "Stop Walking on Eggshells." One of the go-to books for people with a BPD partner. Her silent admission. She eventually started giving me heads-up when she wasn't feeling right or when a possible trigger was coming up on the calender. Basically, in one month, we went from me d--kishly throwing down the gauntlet to her finally sharing. You know, instead of her digging in her heels and telling me to just leave.
So if you notice that your wife tends to snap back relatively well from her bad episodes... .then yes, it's technically possible you could regain her trust. Your mileage may vary.
-ngu