How does a reverse mortgage work?

I have a equity loan of 15,000.00. It is coming do soon. I am 70 years old and had been working, but now I am unable to. I am behind on my property taxes two years, soon it will be three, then my house can be sold. I do have good credit, I have been thinking of a new mortgage as I no longer owe on the first. I have lived here for over thirty years. My problem is I don't have prove of income anymore except social security 815.00 a month. I have two roommates which gives me 640.00 a month more but is not considered income. What do you suggest?