Am i supposed to allow my children to be tortured by their superintendent and their teachers?

My son was put into a class where the teacher is obviously racist again native Americans

My son have came home in tears begging not to go to school anymore.  I have talked with the teacher abd superintendent and their claiming my son is lying.  He’s never had problems in school only this year with his new teacher.  You wouldn’t let him finish using the bathroom and he ended up peeing his pants.  I don’t know what to do please help me!!