You have no obligation to do so. Is this a conditional green card (that is, were you married less than 2 years when the green card was granted?)
You do not have to notify USCIS about your divorce. Since your wife's green card was conditional, she will have to self-petition to have those conditions removed and that is when USCIS will become aware that you have divorced. So long as she can prove that she entered into the marriage in good faith (not simply for the immigration benefit), she should be able to have the conditions removed.
I agree with my colleagues. You have no obligation to report any divorce. Remember the I-485 was an application filed by the beneficiary (your spouse) and she bears the burden to maintaining her status. As to the matrimonial legal questions, I suggest you contact a divorce attorney in your state who can advise you as to that component of your posting and comment. Good luck.
Legal disclaimer: The statement above is provided by CC Abbott is based on general assistance and not intended to be a legal opinion because not all the facts are provided. The person requesting information and all others reading the answer should retain an attorney who is permitted by the state bar within the jurisdiction who can examine the complete facts and provide a legal opinion on your case. All information provided in the above answer and other information provided by CC Abbott does not create an attorney/client relationship within any state of Federal law.