Great advice from everyone. I will only add that the lien doesn't really mean squat until you try to sell your house, which I'm assuming you aren't going to do since you just put a pool in. Don't lose sleep or let him bully you with that. You can get the lien released (if he can even get one) after you resolve the money part of this. Sounds like a court date is in your future. Good luck and stick it to him.