Hello, lanada45, and welcome to Psych Central! I think you need to just lay the cards on the table with your sister. It sounds like she is a master manipulator. I suggest you tell her that you want and in fact need to get out, and you are going to. And do it! And don't feel the least bit guilty. If anyone says anything about your not being with your sister, then you can say, "Contrary to popular opinion, she is capable of staying by herself." And move on.....

If she acts like a brat, then just ignore her. Is there any way you could move into your own place if you need to? You need to set some boundaries with her. I don't want to make this suggestion sound like manipulation of your own. But you might need to say, "Sis, you if keep acting like ( whatever ), then I might need to find my own place to live. And be prepared to do it!

If you can't set these boundaries on your own, then I suggest you meet with a therapist for support. You need your own life and rightly should have it!