Is this too far or what?

im an 7th grader and my mom is over protective she realy cares about my grades as i do too but this last semester i got like a 2.0 and the first i got 3.1 then 3.2 nw it's gonna be like 2.0 and she said if i get 1 c she will take my xbox360 away and i know she will hit/spank me. when she spanks me i get realy mad at her like i just want to punch her in the face (she usaly hits me with a belt or slipper like 10 times) while she hits me she yells and stuff. im 13 and im not sure i can keep this up.btw she said that if i told anybody she would Knock all my teeth out.