What can I do to prove that someone is slandering my character and for defamation of character?

I am a lawyer in CT and practice in this area of the law.  The proof that is admissible in court is either written or oral testimony.  If people will come to court to testify that the defendant is slandering your name and saying things about you to them, you have good evidence.  you will also have to prove that the people that this defendant is disclosing untrue facts about believe them and that you reputation has suffered.  I suggest hiring a lawyer to review any written documents you have (emails, letters) and/or people that will testify for you and decide if the case is worth pursuing.