I see a few problems.

If your first post is anything like the communication you had with the buyer, it leaves lots of room for miscommunication . ( as in all run together and difficult to read. )

E mail is difficult enough to get communication right, text is much worse it seems due to limited space. Besides, if someone has a phone number, call them by voice that way misunderstandings don't take on a life of their own.

Spending the deposit isn't the fault of the buyer.

Unless there was a written agreement ( on actual paper ) as to what is going to transpire, the deal is unclear and each party will have different expectations.

And, it seems that older formerly high end cars bring out odd buyers.