Please... I need comforting?

My whole life is pretty much great. I ranked as a genius on a professional IQ test, I have great friends, all except for my family. My mom has violent mood swings, my dad is abusive and has anger issues, and my sister tells on me every chance she gets, no matter if she trips by herself, she'll snitch. One day one of my neighbors called Child Services because they saw bruises on my neck and heard screaming. It was because my dad was throwing me around my room by my hair and squeezing my neck. I had to lie to Child Services about what happened and that my dad was just "trying to get me to look his way", which was half-true. I overheard her calling me a "spoiled little brat" to my mom and they laughed it off, but deep inside, I'm scarred and I will always remember that my dad beat me with a thick, leather belt until my butt bled. My dad doesn't think he abuses me. But, on the positive note, this happens only every other month. Just today I accidentally spit a sunflower seed on my sister's face and she had me grounded. My mom was yelling at me, calling me a "sarcastic, ungrateful, hateful, little girl" and she slapped me. I don't want them to get arrested or me taken away, but please, help me feel better. I have thoughts of suicide a lot. I think that it would be nice to have me out of the world so that everyone else can finally have a better life because I'm just a mistake. Please help me.