Hi
Monroe, I'm sorry to hear about the troubles you're having with your sister, but I'm glad you found us and want to welcome you to the community!

You're not alone in the way you feel, a lot of people myself included know what it's like to be on the receiving end of abusive behavior that other people in general don't see. "It's hard on us when other people do not experience the same the same behaviors we do, so they don't understand how we feel."
If you don't mind me asking, has your sister been diagnosed with BPD? If so, it's she in therapy? If not, how did you learn about her possibly having BPD?
Have you two always been very close? And if you don't mind answering, how old are you two?
If you are not that familiar with BPD, this link has a lot of good information about it:
The symptoms and diagnosis of BPD. This might help you start to understand her crazy making behaviors.
When a family member has BPD, it really can affect all the other members of the family. To help deal with the issues surrounding it, you should check out this discussion board:
Healing board: for those with parents, relatives, or in-laws with BPD. You'll find other members who are dealing with the same issues for support and senior members that can help offer advice so you can have healthier interactions with your sister. Read as much as you can, and then when you feel comfortable feel free to post as much or as little as you want.
There are a lot of people here that are trying to cope in the best way with the person with BPD in their life. I hope you can find some of the help and support you are looking for here. Also, here is a hug for you simply because you deserve one.