Wow i'm not yet in college i have two more years in my hell hole of a highschool but i deffinately know what your going through except im 16 and my little brother is 9 but the same exactthing is happening to me. Like 2 weeks ago i actually told her if she did one more thing to me i would leave the house and she whipped me so i packed my clothes teared all my posters and left all my baby pictures of me and her on her dresser and left to my best friends house. Although my dad picked me up that night i knew i stood up for something because parents can't just call us failures and all these mean things to get our attention. So i stood up to her and now we treat eachother with respect. I am not telling you to run awaya but just stand up to her respectfully and maybe things will change. But remember doing the same thing everyday and expecting things to change is the definition of insanity! Good luck