Speak with an attorney. See if your ex-husband will sign a quit-claim deed. If not, you can still sell, but BOTH of you must sign the listing agreement with the Realtor.
Let me know if you are curious as to the value. Remember Zillow is not accurate -- not even close. Or if you need the name of 2 good real estate attorneys.
Eric Axelson, Associate Broker
Kurfiss Sotheby's International Realty
In CA (check to see if also in your state), owners can do a Quit Claim Deed. Your ex husband would need to sign the Quit Claim Deed to deed his interest to you. This would remove him from Title. If you can get him to do this, once he's signed, make sure you take it to the county recorder to have it recorded so it is legal.
You need to be working with a reputable real estate attorney. The question you are asking is a legal matter and under the law real estate agents cannot provide legal advice.
I can provide you with an array of referrals, please contact me privately for any contact info.
Coldwell Banker Preferred
A deed is a document of action - the seller gave you and the (ex)-husband title to the property through a deed. You have title, your (ex-)husband has title.
Neither of you have power to remove the other from title, because the way you change title is through a deed. One of you can "deed" the other their interest, but it has to be a voluntary act.
So you do need an attorney, because your other option is to make the loan payments on time. But you can't change the fact that you and he own the property together: you can't dis-own the property for him,
All the best,