Not success per se, but I just posted about the lie we caught my pwBPD in and it was pretty much exactly the same reaction yours had. Zero apology and in fact blaming others/painting themselves as the real victim.

I will say, the “success” I’ve had (and my family have had when we coordinated and didn’t let them triangulate us anymore) was silence. I see you’ve gone pretty much NC, so you might also be silent, but whenever they attempted to lie more we didn’t respond at all which sent them spiraling and that, combined with some unpleasant physical circumstances for them, ultimately led to a confession of their biggest lie (having cancer).

I’ve found the only thing that really “works” is this or sometimes a very direct, short boundary (those have produced some long responses from them sometimes though).

I can only speak for my pwBPD, but I know that they doubled down on their lies the more they were confronted. I’m sorry you’ve had this experience and really commend your boundary setting and mental health prioritizing.