How do i deal with this the right way?

Okay, i have such a problem. It might not be very big to toi but to me, it is huge! I have to older sisters. I adore my older sister. My oldest sister is just a b****. I know i shouldn't call her that but at times, she is. Since i won't say her name, i will call my older sister Hannah and my oldest sister Mary. Mary is just so disrespectful. She clams that she loves us, but i can tell that she really doesn't. She isn't afraid to argue with anyone. She has slapped both Hannah and i across the face and claimed it to be an accident. Whenever i try to talk to her about a serious issue, she will just argue and swear at me under her breath. I feel like just slapping her right across the face as hard as i can. However, i know that is not right and i will get in serious trouble. What should i do? How do i deal with her when she acts so b*****?