Breath. Sounds r.i.d.i.c.u.l.o.u.s. but...it works. Focus, think, concentrate ONLY on drawing your breath in slowly....then exhaling it slowly. Do it several times, at least until you begin to feel calmer. Which - promise - you will.

Then, find images on your computer/phone that make you feel better/calmer/laugh. Oceans, mountains, surfboarding, Chris Rock, Louis C.K. - whatever makes you feel GOOD. Look at that them for a bit.

get up - walk around - get a drink of water. If you can, watch/listen to a funny TV show/movie/comedienne that you like.

Check in to DBT - it's supposed to be "the thing" for BPD emotional dysregulation.

Sorry for your bad news.