Hi bleu,
I'd like to welcome you to bpdfamily. I'm glad that you found that the forun was helpful and you decided to join
You have good questions, I don't believe that it's over, the pendulum swings both ways, you'll be split white again, it's difficult to say how long though, it could be days, weeks, months, years and i've read some accounts on these boards that they heard from their ex pwBPD decades later.
The manipulation is a good question, a pwBPD don't have control over the disorder, you've probably read the term fog on the forums, fear, obligation and guilt which is emotional blackmail. My advise is to read as much as you can about the disorder, the behaviors are not personal to you, it's something that your friend is going through, depersonalize the behaviors. That being said.
We can understand why our pwBPD act the way that they do, we can still have our feelings about the behaviors. I think that you're doing the right thing with talking to people that understand it because it helps to validate your feelings, your friend is not capable of that and will likely blame you for your actions, it's confusing. It helps to get realistic feedback from non's.