Call your title company right now, if you have contact info or leave a message for them to call you ASAP, and ask them to call him and request he give the title company POA to close on this transaction for him, so the seller doesn’t even have to come in Monday. If he’s willing to, they will come to his house with a notary, to sign the POA paperwork. Over and finished with.
If he won’t, have your wife file the lis pendens today online, to put a boat anchor on him being able to complete his sell of the 100 AC or the other 80 AC property, and to be at the front of the line ahead of the title company, and the other party (you said three would sue), to collect on your judgment you’d win in your suit. Don’t tell the title company you plan to do this. Paperwork to retract the lis pendens can be drawn up to be signed at closing if he still shows up Monday.
He can only have homestead protection on ONE (1) property (100ac or 80ac - if that’s all the RE he owns), so in your suit win, the unprotected one will be able to be foreclosed on to satisfy your judgment.
If he breaches your contract and sells to someone else, you might be eligible to sue the third party under the Tortious Interference torts depending on their actions, but selling would be difficult with the boat anchor on the title, but there are fools born every day who will make an uneducated purchase without a title search.
You stated the three closings were to be completed over the next eight days, so I assume yours was hopefully first, and the 80AC closing has not transpired, so you need to position yourself at the front of the line to collect on a judgment ahead of the other two parties.
Good luck.
