Exit permit

Thanks fred.  Here are the details: 
I finished 1 year of a 2 year contract.  The employer refused to give me health insurance, had me teach overtime classes for no extra pay, he has withheld my salary for May, not paid the end of year bonus, and has just been generally hostile and rude to me whenever I ask about my contract benefits. 
For those reasons, I feel legally justified in breaking the contract.   
There is nothing in my contract about penalties if I break the contract and it even says "if both parties don't abide by the terms set in this contract, it will be considered null/void." 
However, my employer won't give me an EPO unless I sign an addendum stating that I will not teach in Indonesia for 2 years.