I think the reason why I got so upset was because he was trying to convince me that he was a good person. And that I actually helped the guy by answering his questions. He had no direction of right or wrong.
Almost.
He obviously knows the value of good because he's trying to convince you that he's good. He must know what good is, because otherwise he could even attempt to convince you. That means he also knows that he is not good.
You're upset because he is a bad person who knows the different between good and evil, and is using his knowledge to deceive you instead of changing his behavior.