What action can you recommend in my case? (see below)

To take away your husband's naturalization would require U.S.C.I.S. to prove that his misrepresentation was material. In looking at the fact situation that you present, you believe that his misrepresentation was not material because he got his green card through his mom who won the DV lottery. You also state that your husband did not disclose his previous marriage on his green card application. Kindly note that a dependent child who immigrates under a parent must be both under the age of 21 and unmarried. You have not said whether your husband was divorced at the time that he immigrated to this country. Even if he was, a question to be explored would be whether the divorce was bona fide or only done for the purpose of allowing him to emigrate with his mother to the States. These are factors that you and your husband should consider. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.