Ok, Jorici, I have some legit tips.
1. NEVER HIT HER. It will only satisfy you for a bit then you will face severe punishment and be more bitter than before.
2. Be calm and nice. If she sees this as an opportunity to step all over you, let her do it for like a day and when she expects you to act like this every day, become yourself again. This will anger her without you getting caught. She can't say you're being "mean", just different.
3. Gather up all your anger and BLOW UP at your parents. Act like you're the boss, but in a respectful way. Something like "WHAT YOU DON'T REALIZE IS THAT THIS HORRIBLE LITTLE forgetER WON'T GET ANYWHERE IN LIFE IF YOU LET HER LIVE LIKE THIS". They are turning their backs from the future and trying to live in ignorance. Force their eyes open (not literally) and make them change. If you don't, you'll never get anywhere.
Hope I helped!
Also, my sister is pretty cool. Sometimes I'm a richard to her, but I've been trying to be nicer lately.