First of all, the employment contract is valid, my dear, given that one party to the contract is a foreign national, the contract was signed in English with the implied consent of both parties.
Let your boss know that you may lodge a complaint against him any time to the Ministry of Human Resources and Social Security (MOHRSS) or the State Bureau of Taxation for his ruthless way of running business. If he asked
you to go to hell, then:
Please contact the Consulate Service of your local embassy (that depends on your nationality, if you are a British or American, good for you, otherwise you may be in bad luck), initiate a foreign-related arbitration of
The respondent of arbitration bears the burden of proof under this case. If the arbitration didn't work (very unlikely), you may go to the local intermediary Court. You need a lawyer now but that will cost a lot of money in advance.