This is unfortunate. Depending on what the contract says, I wouldn't expect anything serious outside of the EMD. But it really depends on what is in writing.
I had a similar situation, where my client was under contract and decided to back out because the home had major plumbing issues. We sent in a well and septic company to give us a quote on remediating the work. The quote took longer than expected (1 day pass inspection period), and once my client viewed the quote, we know there was no way they were going to fork over $12,000 to fix contaminated water. My buyer pulled out, and the seller tried to force my client to buy the home saying we responded to late, and therefore we had to move forward with the sale or else they were going to sue.
I told agent and her sellers "See you in court"...Long-story short my client ended up having to forfeit half of the EMD ($2500). For peace of mind, we refunded the $2500 to the client although they did not want it. I will tell you it was a headache with the court and responding to the other parties attorney, make sure you have legal representation to streamline the communication.
