Hi Amy, welcome to BPD too

Perhaps, just perhaps, you could try restraining yourself, meaning not reacting, not saying anything at all when you're feeling the heat of your anger. Just don't open your mouth, take deep breaths, then only say things once you've calmed down and thought through it.
It's difficult, but with some practice it's possible.
The problem with us is that we tend to react IMMEDIATELY, without thinking, and we tend to react out of our overwhelming emotions.