HELP AGAINNNN!!!! am confused..?

I had a friend in a chat room, eventhough were apart we built this relationship of true friendship... We are comfortable with each other, sharing thougts and even the wildest imaginations. There are times when we chat, he keeps on saying he wants to marry me...Of course I took it as joke as we used to do..
Few days ago I meet a friend again in one of the social networks, I told my friend abt that new friend (guy). and from that day, he started to act weird. Based on his chats I can feel that he don't like that am chatting with new friend but am thinking that maybe he's just pulling my leg.
Just this pm we had an argument, I can feel that he's really angry already. I asked him what's the problem, he's avoiding my question. Am thinking that he's jealous, but were just friends. He's jealous as if he's my boyfriend....we been friends for 4 months now.. We are both from fresh break-up that time we meet..
WHAT DO YOU THINK WHY HE'S ACTING THIS WAY???
Why is he being possessive?

no matter how you communicate feelings can get involved. whether its chats whether its random texts no matter what it is feelings can get involved. sometimes its easier to write to a person rather than speak to them you can say what you want and get it off your chest were as in person you may be cut off or too embarrassed to say anything. of course he's going to be jealous. of course he's going to catch feelings... and yes he's not your man but he wants to be. don't be surprised why he is acting like this. and don't expect him to answer you either men hide emotions.... so just tell him how you feel. no matter what it is. whether you think hes being to possessive whatever... you can't blame him for why he is acting this way... maybe you need to take off your shoes step into his and see it from his perspective.

Internet friends for girls are ALWAS a joke. Do you think a 'hot' or friendly guy would be siting on the computer all day. Imagine this, he is probably a nerd who has never had a girl look at him. He MUST be getting soooo jealous of his first real friend.

hence the problem with online hook ups friends or others.... you don't have a relationship that's built on reality.... you can't get 85% of the non verbal part of a conversation... so give him digits.. talk to him and say if you dig me ask me out a lets start a face to face.... real deal thing

1st of all . he just jealous.
2ND of all he cant get mad yet because he is not your man yet