what should i do?

so today was totally a boring day nothing but babysitting blah how boring right? anyways... i found out that my two sisters got into a fight again and one of them ran away not taking her kids with her. dont get me wrong but i do accept her i dont love her i only accept her. shes a total bitch and very controlling but she's always been that way so when i go back to california(im in washington right now) i know that im going to have to take care of her kids. i dont mind but sometimes i want time to myself too you know its not my fault that she opened her legs for some guy that doesnt even treat her right i just dont want to have to be taking care of them all the time like im there mom but my mom and sisters say that im practically there mom because i mostly take care of them and there mom doesnt. since i also got into a fight with her(not physically) she still been relying on me to take care of her kids. like she aplogized and all but i feel like an aplogy's not good enough. even though at the time i took it anyways because i didnt want to even look or talk to her. so after that fight or arguement whatever you want to call it she came in my room to talk to me but i didn't want nothing to do with her but she gave me this big as lecture talking about how she goes and does all these shit for me and she wants me to repay her back but im like you dont even have to do that its not like your our mom and she still goes on about that shit so at that moment i didnt even want to look at her anymore i just wanted her out of my room. she gets out of my room only wanting me to aplogize to her but i didnt i just went back to doing my hw and she just left and later on i found out that she called my sister and was talking shit about me and my other sister. but after that incident she still asked me to do shit for her and whenever i say no or i dont have any time she goes off on me about how shes the one taking care of me im just so sick of hearing the same reason again and again its like first off she didnt take care of me my mom did and second off i do hella shit for her and i dont ask for shit in return so im just done with her like literally i want nothing to do with her anymore. even if she does come back im not going to be doing shit for her. she gets really pissed off easily too so whatever. i dont know what im going to do about it when i go back home but for right now i dont care about her im not going to let her ruin my summer anymore then she already has with my life. i need some major help with this shit..