The hardest thing we can do is look at ourselves. Particularly when we feel victimized by the actions of others. I think Cynical One said it very well. Your sister isn't doing any of these things "at you" or "to you" and neither are your parents.
The definition of insanity is doing the same thing over and over again while expecting a different result. You can't control your parents and you can't control your sister. But you can control your feelings, attitudes, actions, etc. If you work on changing the things you can control (yourself), you may be amazed at how the things (and people) around you change.
I have a brother that I felt victimized by for many years. I couldn't understand WHY my parents couldn't see it. I couldn't understand why they couldn't MAKE HIM STOP. It took me a very long time to realize it wasn't their responsibility to make him stop....it was mine. It took me a very long time to understand why they wouldn't take MY side. It took me a very long time to stop feeling victimized by my brother's behaviors. It took changing me.
I wish peace for you.
gentle hugs