You must report it. You know that already. I understand how hard it is and don't judge you at all for struggling with it - taking on a hostile school, especially when your own livelihood is hanging on it, is incredibly daunting.
I may regret sharing this, but when I was teacher training I spent several weeks in a school that was very much like yours. I saw some terrible things. A child with a severe SEN picked up by one leg and an arm and dropped in the corner (he had a special corner where he was physically barricaded in with toys during carpet times) and told "Get in your corner!" as if he were a dog. A TA slapping this child when he lunged at another child in the classroom.
The worst day was when a child the teacher hated and bullied and scapegoated every day was being silly with another child with mild SEN. The teacher shut them both in a small side room, sitting silently at a table, with nothing to do. I was allowed to go in and do a planned activity with them as they were my "focus children" for a part of my training. I comforted them and spent all morning with them. The NT child told me he felt "teyyiffied" when the teacher shouted at him, that he wasn't a good boy and he couldn't learn. He said he never wanted to come to school again. At playtime she sent the class out to the main playground, then let these two onto a small outside area and said "you can run around, but you are not allowed to play". After playtime she sent them back to the side room to sit in silence until lunch time. They were 4 years old.
I cried in the toilets every day when I was in that school and burst into tears as I left the school gates every day. Blowing the whistle would probably have meant the end of my hopes of a teaching career - you were supposed to be tough and suck up the teaching placement, the teacher was the blue-eyed girl of a desperate headteacher, could do no wrong and was an expert bullshitter. But how could I carry on training and trying to become a good teacher, and start my career by turning a blind eye to abuse? I tried to talk to the Head and she stonewalled me. I told the tutors at my college what I had seen and hoped they would deal with it. I don't know what happened.
Do the right thing. Whatever comes of it, it will be easier to live with than the alternative.