What should i do?

Hello My name is Annie..I have been married for 3yrs and with my husband for 4yrs. I have been happy all four years. Me and my Husband has been playin this game called Second Life. Its kind of like The Sims, (if you ever played it)Its where you make your self a character.At 1st you just pick on and then later down the line you can make it to look how ever you want. Well you also get to pick a 1st name and then go thu a list and pick a last name.. Its kool. Well i have been playin this game for about a year. I then got the hubby to play it and he started to like it. Everything was goin good. Then we got bored with it and stoped playin for a few months. Then he wanted to play again. His 1st day back to playin the game he met a girl, Her Game Name is Kacee. She is 38 married and has 3 kids. Her husband also plays this game.. Well every since my husband started to play again he has been talkin to Kacee more and more. They then became boyfriend and girlfriend in the game. Now to some of you that sounds funny. But in this game what you do is make a life. Like its your 2nd Life. (hence the name) You meet other people, like them , get married, build or buy a house. have kids.. and so on... Well since my hubby(steleos) has been talkin to this girl, he has stop showin the Interest in me. He doesnt talk to me like we use to, he doesnt wanna have sex with me. I am the one who is always tryin with him. It use to be i couldnt get him off me..Well one day i asked him about her. I asked if she has said the L word to him. He said yes.. i asked if he said it back.... He said .. Yes. Right there Jealous kicked in. I said he shouldnt say it cause its not right. I never said it to any guy i met on there and i never will. He said its just a game and it doesnt mean anything. I ask him why is it he can talk to this girl more then he can talk to me. He said he just can.I told him i didnt like all this and he shouldnt do it. He kind of laughed at me and let it go. A few days go by and i am standing next to him and i just happen to ask if he thinks about her when he is at work. He said yes, he thinks about her alot. Now i dont know about anyone else, but that isnt something you tell your wife. So i got pissed. I feel like i am losing my husband to someone who lives in a diff state then me. I try and talk to him about this all, About how it up sets me how i feel hurt. He laughs at me. And tells me that him and Kacee never talk about real life things, only game things or about sport, music, movies. Things like that. What i cant belive is how she has told him everything else BUT her real name. But he swears to me there is nothing goin on with him and her. But i just cant help but feel like i am losing him. He says if i keep actin like this we arent gonna be together very long. So do you guys think i am making a big deal out of nothing? Or is there something there?
Can someone please tell me what to do? I really need someones help.