We have a saying here: Don't JADE. Don't JADE means don't Justify, Argue, Defend, Explain yourself when your pwBPD makes an accusation against you.
When you JADE, it tells your pwBPD that they are wrong and will cause them to get very angry. It's invalidating, even if you are right. Even if they don't make sense. Even if their accusation is unexpected. The simple act of disagreeing with them, trying to prove yourself, etc tells them that you are not listening to them.
Here is one of our workshops on JADE to read a little more about it.
https://bpdfamily.com/message_board/index.php?topic=139972.0By just enacting this one communication technique for myself, I've seen our arguments decrease dramatically. Throw in a little validation and my H dyregulations are less frequent, about 2-3 times per week as opposed to the daily blow ups.