Is there anything I can get this guy on besides slander?

I am in the middle of a civil lawsuit against this guy for about $3000. In every email I have sent to him reguarding the money he owes me (from a personal loan) I have remained calm and professional. However he responds with emails filled with nasty name calling and slander. Not only of myself but my family and friends who have all helped this guy when he needed it most. I really hate that it has had to come to this, but he is being plain nasty in addition to refusing to pay the money he owes me. I plan on filing a civil suit, however I want to know what other options I have.