[lilseezie]

You've got nothing to lose by trying to talk your way out of it. Be super nice to him (obviously not mentioning any of the stuff you found out), and make up a story like a close friend decided they wanted to buy it after you'd contacted him for his services, and you're really sorry blah blah blah. See what he says. If he gets pissed or threatens to sue, offer to pay him an amount less than (maybe half?) of what you actually owe him, to compensate him for the trouble. If he still doesn't accept, pay him the full amount and be done with it.