In order for it to be slander or defamation the release of the information would have had to have been knowingly false and done with the intent to cause him harm.
That's not correct as to most defamation claims. What you've stated is essentially the defamation standard that developed from line of cases starting with the U.S. Supreme Court's decision in New York Times v. Sullivan, 376 U.S. 254 (1964). In that case, the court established an actual malice standard for defamation claims brought by public officials, stating: "We hold today that the Constitution delimits a State's power to award
damages for libel in actions brought by public officials against critics
of their official conduct. Since this is such an action, the rule requiring proof of actual malice is applicable." (Bolding added.) Subsequent cases have expanded that beyond government officials to others that are in the public eye.
But as to defamation suits brought by your average Joe, it is neither necessary that the defendant knew the statement was false nor that the defendant acted with malice in making the statement. It is sufficient that the defendant communicated a false fact that injured the reputation of the plaintiff and thereby caused the plaintiff to suffer damages. The defendant's BELIEF that the statement was true is not relevant.