just take this and report him to the police, it depends on you, your'e gonna have to put an end to this story by pressuring the police to investigate it. if the number can be detected through a telephone network that's even better, then that third party (since the party you had the feud with is such a coward and doesn't want to confront u in the first place) will be detected by the police and interrogated he will finally confess who made him do this to you and he will whoever it is he will be in real trouble. Further more you can always appeal the the acquittal of this guy and prolong his misery as long as your'e within the appeal deadline. If he want to sue for defamation he will have to prove that your prosecution was pursued by malice and intent to ruin his reputation. Well from what i gather this guy doesn't even have a reputation lol.
choice is yours!
but ud be better of discussin this things with a lawyer