I asked this before but forgot important details.?

My mother and father are SEVERLY mentally abusive and semi-physically abusive. Somedays they are and the days they aren't, they act like they love me but then all of a sudden get furrious. My two brothers are alacoholics, smokers, and high school dropouts, and I dont do any of that and I get mostly A's and never get cruel with them but they abuse me. Today my father walked up to me and pushed me against the cabinet and I cut my upper left, lower left neck/chin extremely bad. They refuse to take me to the doctor period and the really don't care about me. I dislocated my arm the other day, I slipped on ice, and I actually lost circulation to my hand and it was dark purple and my dad told me to go to school. I went, they sent me home and he yelled at me, grabbed my arm, twisted it, and pushed me against the wall and told me to grow up. It's getting worse and now the school priest wants to get involved because I've been depressed. Anybody know what I should do? I can't let my parents know.