OK. There are a couple of options here.
First, you could sue this person for defamation
. In Missouri, to prove a defamation claim a plaintiff must set forth evidence of the following elements: (1) publication, (2) of a defamatory statement, (3) that identifies the plaintiff, (4) that is false, (5) that is published with the requisite degree of fault, and (6) damages the plaintiff’s reputation. Unlike some other states, Missouri courts require a showing of actual damages in all defamation cases. Proof of harm to your reputation is necessary before you can recover for other related injuries, such as emotional distress. That means harm to one’s reputation must be measurable in some economic way, rather than the plaintiff's embarrasment alone. Proving that economic damage will be the bigger challenge for you.
Second, you can call the police and reprot this person for harassment. Harassment under Missouri law is as follows: "A person commits the offense of harassment in the first degree if he or she, without good cause, engages in any act with the purpose to cause emotional distress to another person, and such act does cause such person to suffer emotional distress." Section 565.090.1
My suggestion is that you report this to the police and see if they will investigate. That is free to you and will certainly stop the harassment from continuing. If they won't investigate, then you can evaluate whether you want to puruse a defamation case.
I hope that answers your question. If not, feel free to ask follow up questions. If so, please remember to "rate" my answer before you go. Good luck.