Slander is spoken defamation (libel is written defamation). The legal definition is a publication of a harmful statement to a third person of and concerning the plaintiff. Defamatory statements lower you in the esteem of the public, harming your reputation. Depending on what the statement actually is, the plaintiff may have to prove damages.

Defamation isn't just insulting someone. Saying "I hate that guy, he's a real jerk," isn't defamatory. Saying "I hate that guy. He's a racist, and he cheats on his wife," is defamatory. An absolute defense to a defamation claim, however, is truth. If you can prove he makes racist statements, and cheats on his wife, then he has no case against you. Another defense to defamation is privilege, which may apply in some situations.

Whether you have anything to worry about depends on the strength of the plaintiff's case, and the extent of his damages. Did your spouse make statements to others concerning the former employee that harm his reputation? Were the statements true? Can the statements be proven? Only a full consultation with an attorney familiar with dignitary torts will reveal the extent of your husband's exposure in this case.