In your case, matters could get complicated, so best advice is to seek out a good Immigration lawyer.
In general,
If you are applying for naturalization based on marriage to a U.S. Citizen, proof of your spouse's citizenship for the past three years, which may be in the form of

    * A birth certificate
    * A passport
    * A naturalization certificate
    * Form FS240, "Report of Birth Abroad of a Citizen of the United States of America"

     Marriage certificate for your current marriage