Newsflash: Seller wanting to lock me in after rejecting counter offer

Submitted an original proposal to the seller requesting repairs and a credit on the home which they rejected so we sent a new revised one excluding the credit on Wednesday after having conversations with the seller. The following day they sent a revision/counter to our final offer, which we rejected and decided to cancel and walk away. The seller then walked back on that revision and decided to go with our offer excluding the credit that was made on Wednesday. We are still wanting to cancel and now the seller wants to keep our earnest money because we are not longer agreeing to our Wednesday offer (that they countered). Is this something they are able to do?