The other responses are correct, but might not help you, if time is of the essence. The third option is to default on the contract for deed. Yes, you will lose your deposit/ down payment, unless the seller is willing to voluntarily release you from your contract, and negotiate a settlement.
Most if not all mortgages from 1988 on have a "due on sale clause" which means that the lender can foreclose on the borrower, should they sell the property on a CFD, without the lenders permission. If your seller still has a mortgage with this clause, they legally could lose the property through foreclosure themselves, especially, if the lender is aware of the CFD. In this case, you would most likely lose your equity also.
The downside to default, is if you apply to a lender, for a new mortgage in your new location. The lender will most likely want to verify your residency for the past several years. They will send a letter to your CFD owner, verifying your occupancy, and payment history. Without a favorable response, getting a new loan may be difficult. Leaving on good terms with your seller will be important. If the seller will agree to consider your time at the home as rent, instead of a purchase, and give a good reference, it might be a win, win situation, for both of you.