Well, you could do a reverse mortgage, and ordinarily I’d say you are a bit young to make this kind of decision. At this age, your payment will be low and the fees will be significant. You should be planning to stay in your home at least 10 years to make this work — AND have enough money to keep paying property taxes and insurance.
Also, because you still have a big mortgage you won’t get a very big monthly check. (The mortgage will be paid off in the process,and your monthly payment will be paid out of the balance.)
Maybe you and your sister will want to get together, sell one home, and live in the other mortgage-free?? That could lower your expenses significantly and you’d have each other for company/help — if the two of you could stand living together!
Another plan, if that doesn’t seem attractive, is to sell your home now while interest rates are low and the economy is recovering and there is a demand for homes. Then put the money in the bank — and move into a senior residence that offers assisted living care, if you ever need it. It’s worth taking a look at some places to do the comparison.