Hi and welcome.
Raging is very common for a BPD, and BPD is often not diagnosed.
This site has a lot of resources and we should be able to help you calm things a lot. The menu on the right has a lot of resourses. I would recommend reading about Validation first - it's a conversation technique to help you both talk better.
https://bpdfamily.com/message_board/index.php?board=36.0The big thing with BPD is understanding that they are VERY emotional people. When they argue, yell, etc they are operating on PURE EMOTION. Just like if your 3yr old yelled "i hate you - I wish you were dead" when you refuse her icecream - that's kinda like a BPD. They mean what they say at that moment, but it's not real. Later they will feel different. So when listening to her - you need to ignore her words, ignore her logic, just listen to the emotion behind it.
Also, there are some great published books around. Try "Stop walking on eggshells".