Seller wants to back out of sale

A contract is a contract--it is enforceable. The buyer can absolutely sue you. He can try to force you to honor the deal--which is called "specific performance." That is sometimes granted in real estate cases, but not always. However, if they can't force the sale, they may sue you for any and all expenses flowing out of your breach of contract: legal fees; mortgage fees; appraisal and inspection costs; if they broke a lease or sold their own home, the cost to lease a new place to live; etc. There is no legal way to get out of the deal without risking buyer suing you.

Suggestion: if your town has a rental market, and if there is some chance you might seek to move in a year or two anyway (it seems you're willing to or looking to relocate for a job), go through the sale and rent in town while you figure out what to do.