I believe that my husband married me for legal papers. It has been exactly one year since he received legal docs to stay in the US and now we are separated. I heard through the grapevine that he was still married in his country. I am unsure of what to do? Should I call INS and remove the sponsorship that I made for him and get my marriage annulled. I don't know how that works? Does anyone?

I would go the INS and explain the situation, have them look up his records, if he is still married in his country, his marriage here is null and void, and so are his "papers" so to speak.

First you need to file for a divorce marry a citizen does make you does not give automatic citizenship. I don't know what his status. If you are sponsoring I think you have to report that you have separated.

Well if he is married elsewhere, his marriage here is void and she doesn't need to spend the money filing for divorce.