Petition the court, it's the quickest & fastest way. The apartment slumlords won't budge without a court order b/c right now they're scoring $440 a month. Have your attorney draft up a short & sweet petition, file it, and the issue will likely be settled (Knowing how quick Grundy County is) within a week or so - unless he objects and demands a hearing (Though I suspect a quick pretrial will take care of that issue as well).
Sorry this is going on, best of luck, and hope this helps!
Your question is not clear if you are a housing choice voucher recipient or a project based recipient. that would matter. First, your landlord is not obligated to remove your exhusband from the lease, he is still responsible to the landlord under the terms of the lease. Perhaps your landlord may consider writing a new lease but having your ex husband guarantee it and then cancelling the old one. It has the same effect to the landlord but it helps you out.