Thanks for posting because debt and retirement is a fact of life that many of us have to face.
Even if the bank would do a short sale for part of the difference you could put the insurance, storage rental and taxes if any on the principle.
You really need to pay a financial advisor a few hundred dollars to help you form a plan. This stress of not knowing your options is health damaging. Most will give you 30-60 minutes to decide if their services can be of value to you. Once we look at the full picture with fresh eyes sometimes there is a way where there is a will. Best to you in every way.