I feel for you man. I'm in a similar situation with someone right now. We've been kicking it for 7 months now, and she even moved in with me. I knew she had BPD fairly early in, and did my own research on the condition so I can see the manipulation when it's happening. Doesn't make it any easier though. I fell in love with the wrong girl.

She has at least two other guys that I know are her longtime "friends", but also FWB. She also maintains contacts with the majority of her exes. She'll say things about these other guys that are negative when talking to me, and it all just feels like a way to manipulate me, and it is. I know that she, more than likely, says negative things about me to these other guys as well. It's a vicious cycle of manipulation really.

She's gone so far as to say that she feels like an idiot for not being able to commit to me, but that she just wants to be single for now.

I wish you the best of luck in this endeavor if you decide to continue the relationship. Probably best to keep it strictly a friends thing though. It's hard to do, trust me I know. I'm living it right now. If you ever need/want to talk feel free to PM me.