Don't burn any bridges. Though, I would be upfront about it with your boss. Let him know that you know he is telling people you got fired. And go from there.
If all else fails this is a great idea:
People get really nervous when lawyers send them letters.
If all else fails this is a great idea:
also, pay a lawyer a few bucks to send a letter about slander with threatening overtones.
You'd be suprised how many idiot small business owner's asses clench right up over legal letterhead.
People get really nervous when lawyers send them letters.