Hi Grace,
Welcome to the boards
,
I"m sorry to hear that you are going through such a hard time. It makes sense that after a life with a BPD parent that you would choose someone with BPD. It probably just fit naturally.
It sounds like you are struggling with taking care of your own needs. What would you say your biggest needs (for yourself, not for the relationship or for your pwBPD) is? What can you do to make small steps towards those needs? Have you considered counseling for yourself to help you work through the low self worth and depression?
We have a lot of great workshops available to help you begin navigating through your relationship with your pwBPD. To get you started, here is a link to one of our workshops on what it means to take care of yourself:
https://bpdfamily.com/message_board/index.php?topic=112473.0