Have you considered, or tried offering to your present tenant on a Land Contract, or contract for deed? After all, she's been living in it, and perhaps would just as soon pay a higher monthly "rent to own" price if she can swing it.
It could be a win/win, even though you've already taken a big loss. Set the interest rate at double whatever local rate is. I have a contract I'm holding on a house I sold almost 4 years ago, and I'm getting 8.5% interest. It has a 5 year balloon, and is due next year in August. They had just gone through a bankruptcy, and couldn't get financing anywhere else.