Should i just ignore my grandma and hate her???!?? HELP PLZ!!?

You grandmother believes you. I'm sure of it. Don't even give that a second thought and good for you for exposing your step dad for what he did. You did good. You don't know for sure that your grandmother said that and you are hearing it second hand from your cousin. You know when you hear things they get distorted and people add their own comments. You grandmother and your mom love you unconditionally. Hang in there. People get all emotional and weird around Christmas and things will get better as Spring comes. It seems people's attitudes improve.