I guess I should have seen it coming. I have been trying to be a supportive friend after very recently breaking up with my expwBPD. After firmly but kindly resisting weeks of love bombing and the odd narrowly averted dysregulation (not to mention Valentine's Day :0 - not to sound unfeeling but what is it with BPD and holidays?), my expwBPD then started kerfuffling with Miss Triangle. Now I don't know what exactly occurred, since the privilege of the friendzone is that I am supposed to be able to not care. Still, I objected in the strongest terms to the Miss Triangle's existence being forced on my attention. Part of why I was so willing to part as lovers being that it enabled me to escape the triangle for good.
I have grappled a lot with this in terms of radical acceptance. Since I know that it is a tendency of pwBPD to create negative energy triangles, I felt that I should be able to accept it. But I never can and never will, too triggering, and the most RA allows me to do is to forgive, perhaps. That is to say, to avoid triangles but not hold a grudge. Maybe.
Anyway, I set a boundary around this, saying that if MT was about to stage a comeback I would go NC for a while, and do my parting and grieving in decent, peaceful privacy. At the back of my head thinking "Great! Let her do the freaking caretaking for a bit". And come back when that is worked through, they have figured out what they are doing, and friendship would be much easier. It would definitely be better for me in some ways and I have resisted it mainly out of sheer stubbornness. I simply don't want to fulfil the BPD self-fulfilling prophecy of abandonment.
So, lo and behold, expwBPD heard me and has removed the offending signs of MT from her life. This cannot have been easy for her since I know at the heart of it she wanted validation for the triangle. Still, one can't validate the invalid.
My question is, what do I do now? This flabbergasts me. As you know, setting a boundary when one is starting from the back foot: years of fuzzy boundaries on my part, weak and inconsistent resolutions, etc, pretty much the last thing one can expect is for a boundary to actually be respected. Now I am in unfamiliar territory. I simply don't know how to act. I know, right

Should I rescind the NC and go back to what I have been doing, being prepared to police at need? Or should I remain firm which I fear would send the wrong message? Advice, please, BPD fam!