Hi bus boy,
I'm sorry that you and you're family are going through a difficult time. I know that externally things will seem different for your exuBPDw, she's wearing a mask, a persona that she displays to the outside world and she doesn't trust others to have them see what's going on in the inside. A pwBPD don't grieve like you or I, grieving gets chanelled through acting out and anger.
We want her gone from our lives, we go out of our way to stay clear of Xw and she goes out of her way to follow us or watch us.
What I'd recommend for you is to contact the RCMP if you haven't done so or if you want to go that route if she's stalking you and your family. The vitriol and anger that she has directed at you and your family is going to die down, if she's taking your sister to court it still keeps an attachment there, it could be that she doesn't want to let go. So she could be going through the only avenue where she can still hold that attachment - court.
Pay no attention to your exuBPDw, the less attention that you give to her, the sooner that this will all go away. Also you may want to talk to the RCMP about a protective order if she's crossing boundaries. I hope that helps.