Confronting an online relationship
Hello, this is my first post. Recently I found that my husband of 13 years has been using FB to chat constantly with a former colleague. I've known about their friendship for quite some time and it never bothered me because it has always seemed very platonic. About a week ago, I borrowed his work computer to edit some things, and clicked on FB to post them. Since it is his computer, he was signed into FB and normally I would just log him out and log myself in. However, this time, I clicked on her name and was shocked to discover that they are chatting throughout the day and after I go to bed at night, and everywhere in between. Honestly, most of their conversation is not alarming--shows they both watch, children, even him updating her on dinner plans we had. But there were a couple of things, said primarily by him, that stepped over the line--complimenting her looks, etc. Then, one item said something along the lines of checking several times to make sure he did not accidentally send what he had just said to me. I am absolutely certain from what I've read and because she lives so far away that there is nothing physical. However, it seems to me like he's become very attached to her and it has made me extraordinarily anxious.
I have not confronted him because I just don't know how to tell him that I snooped into his conversations. I also am certain that he would dismiss my concerns because as I said I really do feel certain that there's nothing physical and I honestly believe he would not cross that line. In the meantime, however, I am actually making myself physically ill thinking about it and obsessing over it every time I see him pick up his phone. I have checked their conversations since this time (feeling disgusted with myself for doing so) and have not seen anything too suggestive lately, but today for example he was griping to her a little bit about me not giving him very much space last night--which he and I had discussed half jokingly.
I would greatly appreciate hearing from anyone how they think I should proceed. I think I need to discuss this with him if for no other reason than to get my own anxiety under control. I just don't know how to do it without confessing that I read personal messages. I would especially appreciate hearing some men's perspectives. I think what I'm looking at is bordering on an emotional affair, and I really don't know how to convey to him how that makes me feel because I think it's just too easy to write it off if things aren't physical--there are so many studies that show such affairs bother women more than men.