Quote from tomdavis:
The guy called you "an asshole and stupid"... and you want to sue him for what? ...Telling the truth?
2nd that. And maybe we should all sue the OP for making our society so litigious.

Naturally, I would take a different approach. I might put the email with the loser's name up on the web someplace that gets hit by search engines, while hoping that potential employers would search the web for a name. Perhaps it would be a good (hypothetical) idea if I let folks know what sort of person they are considering.
Just what the court system needs another useless lawsuit. I'd call him back and tell him where to stick his little cry baby rant, and that he should hope no one ever calls asking for a recommendation as you will play the message for them.