I'm guessing that you've tried to tell her the way you feel? Have you tried writing her a letter? I've always found that i can give a much better account of myself in a letter than i can face to face because in a letter no-one can interupt you and make you forget the thing's that really hurt or bother you. Also hopefully when your sister recieves the letter she will be able to relax and read the letter properly and think about what you've written instead of it going in one ear and out of the other (which i find happens alot to people who don't really want to hear what is being said).
I hope this helps you