What do I do?

my mother used to be a very bad parent towards me, and recently, she's gotten better. but i don't think this is a good thing. she was terrible to me and my sister and when i tried to speak up abt it after my sister left( when she asked) she called me out my name. since then, we've had a "good relationship", mainly because i don't tell her the truth. she's mostly glamorizing me or putting me on a pedestal because i didn't leave her. and by good relationship, i mean she tells me everything and i sit there and nod. as the months have flown by, ive realized that she's gotten nicer to me, but so much meaner to my little brother. like meaner than she used to be to me. and i couldn't take that then even though it had been happening for years, i know he can't. there is a time for him that he didn't experience those things that i didn't have, so he's not strong enough to take it and he shouldn't have to be. no one is. i'm graduating soon, and i don't want to leave him here because i don't know if he'll be okay. but i can't take him with me. and i'm scared for him because i don't want to hurt him, but i know i will no matter what i do. i'd love to take him with me but i can't support him and me and my little sister. i just don't know what to do.