The practice of polygamy (marriage to more than one person) makes an immigrant inadmissible and is also an excludable offense. When you applied for your greencard you would have been asked if you had ever been married to more than one person. The same question will be asked on the Naturalization form and could cause your application to be denied. I can not advise you on Pennsyvania marriage law, but in most if not all states, polygamy is illegal. You should speak with a U.S. Immigration Attorney about the details of your case and to a Pennsylvania Family Law Attorney to see if your marriage to the woman in the U.S. is even valid.