I need advice

I need advice I started stuttering when i was 12 nothing major back then until recently i am now 17 and i can't even speak sometimes it's fucking annoying it's driving me insane when i can't get the words out im screaming "FUCK" in my head everytime i stutter and it has gotten to the point that i punch my self sometimes out of anger and tiredness it is preventing me from contributing at school when a teacher ask me something about "x" i just say "i dont know" even though i know the answer because i'm too scared to stutter infront of the class and embaress myself i can't even tell my patents how my day was and so on.