Actually, this situation is a great way for you to prove that you do have the necessary maturity. Ask nicely and be professional. Calling him a "ba$tard", creating threads with titles like "Some people really make we wanna kill them" and suing him over an argument does not scream "super-professional-attitute" to me ... actually, it sounds more like 17-year-old-kiddy.
EDIT: Or maybe just ask him to be your friend on Myspace. I think thats how conflicts are resolved these days. Remember to use at least five exclamation points and also lots of smileys like "^_^", "XD!!!!" and "^_o''".
