LEGAL ADVISE

@cawley it might be time you got a lawyer, he has made it clear that he is going to try to hold your reputation hostage over this, the idea of pay me or I trash you has legal ramifications, slander is a big deal, do you have this threat in a text or email?
without proof of his accusations, that's all they are, you have rights here too
tell him to either bring you the car or eff off, the only other thing I can think of would be to have a third party do some sort of an appraisal of what he is claiming is wrong, see if he is willing to legally put what he is claiming in black and white