Honestly I would just let it go. I think you are over thinking the matter. They really all might have just been friends along time ago. I went to a provide high school and it was hard for me to understand that for instance people in high school associated with the opposite sex much more frequently therefore it is less of a big deal to have companions on Facebook and such. I'm just saying you loved your wife enough to, at one point on your life, devote your whole life to her. I would not let a feeling of pride or whatever it is that is bothering you keep you from giving her the benefit of the doubt. However, like I said I really don't know the situation your facing.