Interesting situation.
In my experience, what you are going through is why I don't deal directly with the counter party, whether they are the seller or the buyer. If you have an agent, they are your representative. Tell them what your terms are and let them represent you. I do not get involved directly with the buyer/seller.
As others have said, until both parties sign the contract, nothing is solid. And even after signing, things can and do go sideways.
People think I'm an idiot or something, because all I do is cut lawns for a living.