I think i need help. i have the urge to kill someone?

ok so i have an extremly strong hatred for someone. and i want to kill that person. i don't know whats wrong with me. i planned a way to kill them, with hydrofluoric acid. maybe not kill them, but hurt them so severly they will need help with everything they do for the rest of their life. im horrible person, but i feel like im psychotic. i feel like im about to snap and really hurt someone or myself please help me.