It is clear your prime intent is to sell the home.
As others have shared with you, that is going to be very problematic at this time.
You have four other options. Since all of the options have consequences, only an attorney is qualified to discuss them with you.
In your discussion with your attorney get a good understanding of:
1. Who owns the house.....really.
2. Who is responsible for the mortgage?
3. Are any persuasive mechanisms available
4. Can you reach an agreement for a fixed buyout right now, without a purchase offer?
5. In two years what will the situation be
6. What is your long term goal
7. What option(s) is most beneficial to you and those important to you.
This opportunity to sit with an attorney will be an exercise in acute listening.
In addition to what is said, make certain to hear what is not said. The action most appropriate will be cloaked in the description of the cascade of events that CAN happen should you choose a specific option. It is indeed this element that will create for you the leverage you need to get this home sold.....EVENTUALLY...most likely over a year away.
Without choosing to resolve this issue you are stuck! You can not buy another house. You can not move. You are very likely upside down if you purchased in 2007, the peak year. It's not going to be easy. It won't be pretty. But it is a pill you must take. Waiting only reduces the options available to you.
Wishing you the very best outcome.