I think you should immediately contact Leslie Struthers at Guaranteed Rate– She will let you know quickly if you qualify to refinance your mortgage based on your retirement income. If so you could get a 30 year mortgage (yes, I know you will never pay it off!) that would be the cheapest way to stay in your home as long as you can.
Her contact info is Leslie@rate.com or 312-379-3526.
If you can’t refi, keep in mind that cash will be valuable down the road. And that this might be a good time to reconsider your living options for your life in retirement — ie, a time to sell and move into some form of senior living community.