marrying a Mexican

this is this problem: I am engaged to a man from Mexico & he is living in the states without any papers & he already has a wife in Mexico which he must go back to Mexico to divorce. My fear is that he will not be able to return home to me without some legal difficulty. I would like to know if there is some loop hole that would get me past this issue. I want to marry him & be a family. He's been here for 1&1/2 years, with a steady job,with proof of pay stubs. Is there any way to return to Mexico with him, marry there & return back to the states? please help. thank you