It will depend on exactly what your contract with the buyer states.
You need to consult an attorney in the present state as you have presented them. My guess is they could take you to court to recoup the money they have spent. The question is, how much will it cost them to recoup the amount of money they have spent.
I don't think they can force you sot sell, but they can "take this to court"
If you decide to sell in the future, I can navigate you throughout the process so you do not find yourself in a similar situation.
"Schmoe Know Homes"
It will come down to what your contract says or doesn't say. In most cases, the buyer has multiple out clauses for inspections, due diligence, financing, just to name a few. Rarely have I seen a contract that contains an out clause for a seller.
No matter what anyone here says, have your contract reviewed by an attorney and then consider your options.
You signed a legally binding contract which the buyers then took to mean they should spend money on appraisals, inspections, moving expenses, etc. By attempting to reject the contract, you could be liable for their damages.
You should have made the sale of your current house contingent upon finding an acceptable property to purchase. That's fairly standard. I'm guessing, therefore, that you probably didn't have a Realtor representing you.
I'm not a lawyer, so this isn't legal advice. However, contracts are contracts. You agreed to sell. If there was no "finding a home of choice" contingency, then you're in violation of the contract. And so not only can the would-be buyers sue, but they're likely to win.
On the flip side, it's nearly impossible to force someone to sell a home. But you might find it a very expensive and uncomfortable process.
See a lawyer.