If the property was disposed of in the divorce, then the property was disposed of in the divorce and it cannot be changed. If the property was not disposed of in the divorce, then you have potential problems.
The home? That really is going to depend on the language of the divorce decree and what paperwork was involved. Sometimes one party is awarded the house and signs a "Deed of Trust" which states they pay the mortgage and if they fail to, the other spouse (who was probably also on the mortgage) can foreclose on the home...
Try reposting or sitting down with a family law attorney in your area. Many give free initial consultations and the possibility of losing your home is well worth an hour of your time in an attorney's office. Take the paperwork with you so they can review it.
Disclaimer: This answer is intended for informational and educational purposes only, and should not be construed as forming the attorney-client relationship or as legal advice. This attorney is licensed in TX and you should consult an attorney licensed in your state before taking any action.
In the absence of fraud, duress, or incapacity, once a divorce has been finalized and the appellate timetables have expired, neither side can re-open the case or modify the terms of the property division. In Texas, a person wishing to appeal must usually do so within 30 days of the date of decree or else the right to appeal is waived. In sum, based upon the question as posed, the ex-husband should not be able to unilaterally modify the terms of the decree regarding property awarded to you.
Notice: The foregoing is for informational and educational purposes only, and does not form an attorney-client relationship or constitute legal advice.