im hearing voices

i hear voices in my head when my moms boyfriend is here. no matter how many times i say stop they keep talking. they tell me that he won't stop he'll keep hitting me and that i should kill him
everytime im close to him they say "he here, kill him now, it's your chance.
everytime he's gone they say "he's not here, he's gone you got nothing to worry about, untill he returns when he get's back he'll start hitting you again, he's not dead.
everytime i try to tune them out they get louder they won't stop. i can't sleep at night