Hi TheMaskDropped,
De-escalating a fight can definitely be tricky. A workshop revolving around "How to deal with an Angry Partner" was just launched a few days ago. I'm not sure, but I think you may find some useful advice in regards to your question there.
You can find the workshop through this link:
https://bpdfamily.com/message_board/index.php?topic=309757Hopefully it can give you a few good tidbits in dealing with these situations.
- Staying Steady