Confused And Hurting And Sad

well I am not sure I am at the I'm not happy and married but here goes.  I am married almost 3 years now.  I'm from US and shes from Canada.  my job/profession takes me back and forth for months on end with visits home every couple of months for 2 weeks.  Recently well as far as I can tell my wife has started to go to chat rooms and meeting others online.  She also plays WOW a lot and meets people that way.  She has become close to some of the guys that she meets one in particular that I am away of.  She asked me some months ago that he is in a bad spot and can't find work in the small little down he lives in Canada.  So she has offered for him  to move in with us but only if I was okay with it.  I kept telling her I wasn't because I would be away from home and having a stranger in my house with my wife and step daughtt of 12 wasn't good imo.  I was under the impression that she has only known him for acouple of months but then she tells me she has known him for about a year....not sure if that is true she might think that if I think she has known him that he isn't a threat to me.  he is a younger guy 22 and she is 33...she says he is a like a younger brother to her and there are not feelings for him.  Before Christmas I was okay with him maybe staying with us for a month or two until he could find work.  During the Christmas break I saw a message he sent her on yahoo saying something like hugs and long deep kisses.....this is right  b4 we are to open up all our presents with her family at her sisters house on Christmas day.....I was so mad I couldn't speak......everyone knew something was wrong.  After the presents were giving out I went down to be basement where we were sleeping for the visit and layed there pretending to read a book.  she came down and wanted to know what was wrong...even her brother in law knew something was wrong and that usually isn't the case with him.  I said nothing ....I don't want to ruin Christmas day.  Some minutes later shee comes back and I confess I saw the note and that I have really insucure feelings about this whole thing with him.  She explains that they Play world of Warcraft together and he says this little cute thing of hugs and deep long kisses to keep the other guys from hitting on her.  We talk a long time and she assures me nothing is going on with him.  I have recently found one of the places she goes to chat which is a bdsm chat site where she is Dom and I am thinking he might be her sub or if nothing else she has a sub there she plays with.  We have dabbled with this life style on and off in our real life and I understand she likes this.  I am thinking at the least she is having an emotional affair with him.  I actually asked if I could join her in this chat site and she said no this is before I went there.  I am spying on her there and I know its not right if she found out i was there she would be very upset.

I am not sure what to do.  I still don't want him to move in with us...she is suppose to be visiting us in Feb but with my work here in the states I am not sure if I will be able to be there.  I can't say he can't come to visit because he is her friend.  She has told me that him moving in with us would be a back up plan if living with his sister didn't work out....which I am not sure if that is the case or just something she is saying for now

I know honesty is the best thing  here and I was very honest when I talked to her during christmas.  We don't talk unless I call...she makes a lot of effort to talk/chat with him and even called during the holidays.  She says that he has some mental health issues and that is why she has become close to him.

I would really like some imput from you guys....I am feeling very lost here and don't know what to do or to do anything at all....she and her daughter are my life and I don't want to loose them