You could sue for defamation and get an injunction preventing the same conduct in the future based on the following law of defamation:
1. The slander (oral defamation) or libel (written defamation) must be false. NOTE THAT IF YOU BRING A LAWSUIT...TRUTH OF THE STATEMENTS IS A DEFENSE THAT CAN BE USED BY THE DEFENDANT. 2. The false statements must cause you PROVABLE MONETARY DAMAGES...not hurt feelings but actual monetary damages that a jury can award you money for. For instance, you must prove that as a result of statements made, you were fired from a job, or were prevented from getting a job, lost a business deal. etc.
Slander or libel suits do NOT, however, require proof of these 'special' damages if the statements are defamatory ON THEIR FACE, that is, they FALSELY allege that a person:
1. Committed a crime.
2. Has a loathesome disease.
3. Is guilty of sexual misconduct. or
4. Is incompetent in business.
You will have to hire an attorney to bring a defamation of character lawsuit as a practical matter.