I am really hoping this is fake because if not, you should report them to CPS. Not even kidding. If it's NOT fake on the off-chance you are being sincere, I will say this:
1) Dont lock yourself in the bathroom to calm down. Instead, call up the mom immediately and let her know that you have an emergency and need her to come home as soon as possible. Or else you will be forced to call the police to come stay with her kids. When she gets home, tell her anything you want: The truth, that you have a family emergency, or that you frickin' have an infection in your ass that you need to go get checked out NOW, for all you should care.
2) LEAVE and never look back. Seriously. Not only is it beyond inappropriate treatment of an employee, it is also an unsafe, nasty and potentially hazardoud environment for you AND the kids you are in charge of.
Stand up for yourself. Are you dirt? Because that is what she is treating you like, you know. But "God don't make no dirt," [in regards to people, obviously

] So you can't stay with people who treat you as such. Period.