What would you do in my situation?

Ok im 18 and I live with my mom my little sister and my moms boyfriend. Well me and my sister share a room cuz we live n a small apt. ne wayz my sister and i dont get along AT ALL shes 13. and shes so rude and disrespectful 2 EVERYONE. well i dont like 2 argue but she does [[id rather fight and get it ova with]] and she like 2 fight 2 but im older than her so i would neva put my hands on her but ne wayz i try 2 lock myself n the room just 2 stay away but its hard cuz she lives like a slob and she really makes the room stink and i would clean up the whole room but shell justt **** it up again. So lately I tried to stay in the livin room but my motha boyfriend always kick me out because he say i dont pay ne bills and he do and the livin room has his t.v and couch n it. I wanna move out but i have no where 2 go. Im savin money up now 4 an apt. but no tellin how long thats gonna be after i pay 4 skool and stuff...so long story short Im havin a break down and i need to kno wut 2 do