Why won't my sister just leave me alone how do you deal with a person like this?

I am 18 and she is 16 and we are probably the most opposite people on the planet. I am very shy/quiet and she is loud/outgoing. She has bi polar disorder so i'm not even sure she understands most of the time that what she is doing is wrong. She used to put me down infront of other people telling them that I didnt have friends and I never left my room because she was always worried that poeple would like me better than her. She fights with my parents all the time which is quite annoying to listen to. She complains a lot about people being controlling or self centered. When ever she is talking to my parents about herself and I say anything she yells at me for trying to make the conversation about me. I am like the quitest shyest person you will ever meet and she seems to think that I am self centered and controlling I am actually a very passive person and I let people walk all over me which isnt really a good thing. I mean is it self centered that I hid my anxiety problems from my parents so they could deal with my sisters. She is constantly concerned about wether or not I am getting in trouble for something because she gets into trouble a lot more than me. I don't understand why she cares so much about what I am doing. When my bf is over she thinks that he controlls the whole house probably because we are in a room she wants to be in and she doesnt want us in there. Today I saw that she had my boots on and I asked her if they were mine and she said yes so I sighed because its annoying when she uses my stuff but I didnt want to fight with her about it then she yelled at me saying that she wouldnt wear them if I would just ask her not to then 10 mins went by and I asked if she would please not wear them and she said that I was overreacting and she wore them out to hang with her friends. I just try to avoid her because she just doesn't want me to have anything good or happy in my life for some reason. My parents tell me I am being really mean for not wanting to be around her and that it makes my sister feel like **** but I can't take the way she treats me anymore. She will find ANYTHING she can to pick at me for and she just wants me to look bad or get in trouble. I don't really care what she does and I'm not worried about making her look bad or getting her in trouble. All I ask is that she doesn't talk to me or touch my stuff or worry about what I am doing....