Um, your sis wasn't merely BPD, she was a raging, controlling, manipulative, Narcissist! Worse still, your parents were enablers of her bad behaviour, as she was the "Golden Child" and you were the "Scapegoat."
You need to re-read what you wrote about how this sack of human shit treated you. Yeah, I said that!! You may not believe it now, but in a short time, you will feel nothing but RELIEF that this toxic abuser is out of your life! No more stupid bullshit! No more stalking! Your ungrateful, cruel parents would be the last people I'd talk to.
10 years ago, you should have gone "No Contact" and been done with the whole lot of them. You sound like a much better person without them in your life.
Wish I could say I was sorry for your loss, but I'm not! I'm grateful you are now FREE, and someday soon you will be too. When that happens, don't feel guilty about it. It's 100% justified to feel relief. There's nothing wrong with YOU, but there is definitely something wrong with THEM!
Good Luck. Welcome to the rest of your life!