Why does everyone call me stupid?

My dad calls me a retard, and that I go into "retard mode". However, he strangled me twice in my life; one time when I was 9, another a month ago. I don't know what's wrong with me, i know I cant sit still, I have hyperactivity, and I'm really sensitive(if you insult me I'm die insde and cry a river, it's not my period.). I say. The dumbest things, I have a poor sense of common sense, I also have an episode every month where at ny house I just go insane, cause my dad either called me names or threatened to hit me. It's like everyone Hates me since I have very few friends. I had to play a concert today(I'm lead), but I'm reconsidering and saying "screw this, since everyone's diagnosing me as stupid or retarded, I'm too stupid to do a concert."