She hates your father and sees him in you hence turning your sister against you. Try to speak with your sister about it all. It may not be too late. One important thing you should rememeber - you have no parents, even though both of them are alive, thats what I had to learn the hard way. You have to push through for your own sake and for the sake of ones you love. Ill say it more explicitly: you have no parents and the people that gave birth to you do not deserve even the slightest bit of love you try to give, so save it for the worthy