Hi, Quantum Leap, and

I'm sorry we got to your post so late. There's been a lot of new people posting, and a shortage of veteran members and staff. I hope late is better than never.
As you might guess, giving advice is not something without its dangers. People with BPD are not all the same, there are different kinds (sub-types) and inside that, every person is different.
I understand your hopelessness, the part I resonate the most with is something like "why would she blackmail me, if I would give her the world?" It is very frustrating.
How long have you been educating yourself in BPD? How long have you been together? These things take time to settle. The diagnosis can shake the person's world, before things can get into place, and the improvement can begin.
Staying away can defuse some intense situations, but it doesn't solve them, she might feel abandoned, and that triggers a lot of disregulated emotions.
What do YOU want? Has the situation changed?
Please keep telling us, so we can know you and the situation a bit better. Try to use punctuation and separate paragraphs, it was hard to read your post as it is, and maybe that discouraged some members. We all have our own troubles, and that sometimes leads us to pick our battles, and choose where to put our efforts.
Don't dispair!