The best approach would be to work with the Creditor's attorney to come up with some kind of agreement.
You can also move to have the stay reimposed or ask the Judge to reconsider lifting the stay.
If the motion for relief from stay has been granted, you no longer have a defense. The time to raise a defense would have been right after the motion was filed by obtaining a hearing date and opposing the motion. The creditor is not required to negotiate with you, but you should at least try again.