contact a lawyer.

for your extension you need to book an appointment with your local field office to get your passport stamp call USCIS to make that appointment. for your I-751 to need to convert the case now to an I-751 waiver since you are divorced now . on the waiver you explain to USCIS that you are converting the case from a joint petition with your wife to a single petition now that you are divorced but you will still need to prove that your marriage was bonifide with your spouse before you got divorced