SIL I HATE HER

so I live with my boyfriend and his parents in cause im trying to get on my feet but I help his mom do chores and her and I clean up after everyone and so back to the story. my boyfriends sister stole some of my cigarettes and so I took them back and this morning she was getting ready for school and noticed I took my cigs back (shes 15 btw) and started messaging me telling me I purposely broke her eye brow pencil and I owe her a new one and new cigarettes and I told her hell no she doesn't even buy her own shit so why would I buy her new shit and also shes been stealing my underwear for months like who does that?! so I watched her leave for school and she starts texting me again saying how im a freeloader and atleast she still lives with her own parents (the reason why I live here will remain confidential) but I just got hello mad. she called me a bad mom last week. now this shit? Idea what to do man I want beat her ass I wish I could😔