Hi codepanda. Welcome!
I agree with Gully Foyle – don't bring up BPD to her. I'm not aware of any situation in which that has gone well.
Now that you found your way here, start by working through the lessons that are pinned as the topic at the top of this discussion board. They can help you better understand the situation, what you can do, and what tools you may want to try using. These lessons helped me tremendously.
https://bpdfamily.com/message_board/index.php?topic=347836.0There's a great community of people here who can help you out along the way as you figure this out.