Can I press charges if someone threatened to me in an instant message? The only thing I know is..10 pts?

I was in an online chat room on a different screen name, pretending to be friends with someone who doesn't like me, but they didn't believe I was really their friend, and they had an incling it was probably me so they said it was probably me. I told them it wasn't me, then they sent me an instant message asking me who I really was, accusing me of being their enemy and threatening me, saying they were tracing my IP and would find out where I live and come and me. Now mind you I am 23, but the guy who threatened me is 33 and is supposedly a mature adult who lives with his fiancee. Likewise, he has threatened me this same way in the past, at times when I was only around 17 or 18, and also stolen my account, written unruly messages to my friends, and erased all my email on 5 separate occasions. Back then I knew nothing about him, but now I know his first and last name and the state in which he lives. My question is, can I legally press charges against this guy if I know only his first/last name, the first/last name of his fiancee and the state in which they live? If so can I file a report online, and how do I do it? Note that the guy is on the west coast, and I am on the east coast.