Y does my family abuse me?

Everyday my parents tell me they h8 me. My brother also punches me ( like in the face) I don't know y they do it. I AM going to kill myself, but I just want to know y they did this to me my entire life. People say I have so much to live for but I'm sick of being everybodys ***** and punching bag and I still don't see a reason to live. Every night I cry, everyday I cry. So y do they do this to me. Btw I'm a 14 yr old girl