[edited]! Do you have a chance to visit the Beijing Bureau of Foreign Experts? Take all written stuff with you like contract and anything else relating to that "school".
Be careful though. Only go there if you have a valid residence and work permit!
And make some noise before you leave them, tell students and parents! If you are in real trouble, you can also call your Embassy and ask for help/advice!
Don't pay any attention to what they say regarding your "colour", it is irrelevant!
Good luck!