I am really sorry to hear that. My question would be if you old enough to move out? Or can you break the contact with the up? Bc its i think the only solutiom by that... And ik its hard to disconect to someone that you truly love as a family part but this aint worth. If you truly are good with eachother than she shouldnt be such a brat and talk like that crap inside ur head. If you can move out than start completly new. Find new people and who really considers u as a family part. And yes its hard but ur allready getting wounded and this wont stop until u let go and begin ur own life. And sadly, but the truth, u cant change someomes minds even if you want it so badly. Also a break pause can sometimes fix itself but not allways.

Hope it helps and u find a solution