DB33,
I'm sorry you are going through this, it is very hard to deal with such a change in the relationship while living together. No wonder you are feeling sad and conflicted, I would be, too.
At the risk of being blunt, I don't think "hope" is going to cut it for you and your girlfriend. If she has BPD, she will need committed long term therapy to manage her behaviors, and you will need to spend time learning new ways to cope, and likely undergo therapy yourself. There are success stories, but it takes hard work and time. Are you
both ready and willing to commit to taking that road? If so, we have resources to help you.

If not, I encourage you to start thinking about what you want and need in your life, and in relationships. Focusing on her and what she is doing won't help you heal, won't help you move forward. You can't control her behavior, no matter how kind and caring you are. I know, I've tried.
Keep writing DB33. I know it hurts. I didn't want to let go of the dream, either. We are here for you, and we care.
heart