Can I file a Lawsuit against my ex boyfriend

I was in a relationship with a coworker a married man..we were together since December 2017..in April 2018 the wife asked him to move out. He went to live to his daughter's house which is on his name.. at the beginning of August he decided to end our relationship because he didn't want to divorce his wife he didn't want to give her half of what he has. The problem is I lending him my credit to buy some furniture for his grandson but he still owns me $600 that he doesn't want to pay..besides that he destroyed my reputation at work..telling every one that he left me because I'm a golddigger.. which is not true there's no proof of that statement. I want to file a lawsuit for defamation.. Psychological Damage...He has more than a million dollars in an investment retirement account..and a house on his name.. Do I have a case?