My niece did this at a day care years ago. She would scream and cry and it was heartbreaking. At first, we thought it was separation anxiety, but she was always such a bright, happy little girl and this was the first time she ever acted like this.
One day, after my sister dropped her off, she called me and we talked about it, and said whatever it was, it wasn't worth it. We went and picked her up, unannounced. She was sleeping, and one of the workers went over to wake her, and smacked the mat she was sleeping on so hard I thought her hand would break. She screamed her name and said, "GET UP!"
My thought was, "If that's what they're doing when people are here, what are they doing when they aren't?"
She saw us, and came running up to us, just crying.
I say go with your gut. I think if teachers have already been using profanities and calling him names, you have enough reason to pull him out. Now his wrists hurt. I'd pull him out and report them. He's little. School should be fun, not scary, and he's telling you things are bad. Listen.