You should speak with a personal injury attorney; what you describe may be defamation, so you may have a legal claim for damages or compensation. Defamation is the knowing or intentional making to third parties (other people) of untrue factual statements that damage a person's reputation and/or make others not want to work with him or her. Telling a potential employer you were terminated when you were not would be a factual mistatement that could damage your reputation and could be defamation. Note that opinions are not defamation, no matter how negative--only untrue facts. So the former boss may express his opinion that you should not be rehired, but may not lie about the circumstances of you leaving employment.