my controlling parents

I'm 16m and honestly don't know where to start. before my mom started dating her boyfriend it was perfect no arguments and no forcing things. once my mom's boyfriend started getting comfortable around us and my siblings he lied to us saying he would beat us if we did something wrong (I'm the oldest and i was 9 years old) anyways that doesn't really matter now. i wanted to ask if I'm overreacting about wanting to move in with my grandma. first reason i want to move with her is because they are overly controlling with all my siblings for example my parents make me and my siblings go to bed at 8:30. second, i also wanted to ask if this is considered abuse and/or assault, so pretty much anytime me and my mom's boyfriend get into a verbal argument and a i have somewhat of a tone he will either slap me in the face really hard and threaten to slap me and i also i remember in 7th grade when he was on a business trip i got really mad and call my mom the b word and i sincerely apologized to her and when he got back and found out i was going to sleep and he comes in pours water on me, drags me off my bunk bed, literally beats the hell out of my with the belt and then i kid you not PUNCHES me in the fucking face i wish i had a photo of my lip as proof.(that's only two of the times he has hit me) and there's much more like him manipulating, being a bad influence for example smoking and drinking and then he wonders why I started vaping. so, my final ask is should i try and move in with my grandmother or am i overreacting. (sorry if this is very informal this is my first time doing this)