Why couldn't you refinance? Not enough equity or not enough income. Depending on the divorce decree some lenders will accept the order showing you are no longer responsible and your exwifes income is adequate to cover the debt. However it is harder and if she defaults you are still technically liable. It is a delicate balance because both of you have to agree. If it wasn't amicable even the best realtor will have a tricky time keeping you both happy. Good luck and I hope it works out.
Is the house listed with a realtor or for sale by owner? Realtors have a lot more tools in their belt that a fsbo. Price is crucial. Must be very competitive.
Let your agent be a buffer between you and your x.
First, trust and follow your Realtor's opinion as to price. Second, if you just want "out", offer your ex the first x$ of equity, then deal with the balance. Then your ex may be more agreeable to any offers you receive.