Hi
I found a great tool that was told to me by my mom's Dr.
I asked him how I could respond to my mom when she is pushing my buttons. The Dr said to respond with "I am sorry you feel that way" I could not believe how that worked as my mom did not know what to say. And I just kept saying it when she has time to think of something else.
My therapist suggested something pretty similar for me!
I think that's where I've found that most of us are pretty defensive... . when we have to defend how we feel. It's can also be pretty easy to invalidate a pwBPD when it comes to their emotions. So I think this kind of statement says "you have a right to feel however you feel" and allows us not to have to try to change it.
Glad it worked for you.