Internet case example(s) #716: Person explains situations where they are victims of child abuse, and pretend-dads loaded with stupid thinking go "SHOULD HAVE LISTENED TO UR MOM" or "stop disobeying her!"
Tell the police about it yourself and explain the whole situation to them. Without your mother.
Or tell a teacher or school guidance counselor. You can still contact them during the summer.
Going through more of the posts on page 1, it seems incredibly absurd of her to yell at other kids. If I got in trouble and I had friends around, my mother would just simply and kindly shoo them out of the house then proceed to reprimand me for whatever I did that was probably stupid. I'm going to take a highly educated guess and say that at least one kid told their parents, and those parents will likely raise a flag about this to the police.