Wow, it really sounds like you really feel stuck. You have also done your homework on BPD but one of things that stands out is that some people need to take care of their needs first. Learn to put yourself first instead of him. Know that his behavior is not about you even though he claims it is. As you said, he is a liar.

Is there a way for you to work with a therapist on your goal separating yourself from him? If he is not working or only working sporatically, perhaps you would be better off without him.

I wish I could offer more support. Going through something similiar, but I am staying with my sister. Believe me, I have had he urge to bolt more than once. Working on my own goals to find a more stable emotional environment for myself and reaching out for help and reaching out and giving help where I can has been a real boost and lets me know that I am not alone, that I won't be stuck forever.

Keep posting and let us know how your progress is going.