Interesting... . I have yet to "word" my boundary's. I just do them... . I know at some point I'm going to have to get practiced at how to word the boundary without "provoking".
I'm guessing saying it in a monotone... . or somehow acknowledging her emotions will be important.
Trick question.
It's not a whole city of independent people, it's a city of emotions of one person (our pwBPD) encroaching on us (the nons).
Confronting the city of emotions is like yelling at a crowd, more trouble will ensue instead of resolution.
Better to go to the source. What brought the crowd there? What triggered all these un-regulated emotions?
I would launch dialog asking for my pwBPD to examine her emotional state, get her aware and open about her anger/encroaching, and then remind her to not make decisions in that state. With a little luck - and maybe weathering an extinction burst - I can see the dysregulation pass.
And then I strike - once the crowd of emotions disperses I swoop in with my fencing material and put up a Boundary. A politely worded and practical request, or a serious and positive-sounding statement of reality-based consequences of future out-of-order behavior. Maybe both.