FYI.... if this can help you in anyway, about 10 years ago, I started searching for my Xboyfriend through classmates.com and I think i did a people search on him.
I had absolutely no intention of hooking up with him. But I was very curious about him. where he was, if he finally straightned up and flew right, or was still in the heaps of drug dealing and mooching off people. As it turned out I found out through friends of his I found on classmates, that he was not doing well, in and out of jail and just in a bad place.
He was my first love, and I was curious. I just was. But I never had any intention of leaving my husband and family for him.
My husband found the searches and he confronted me about it. He was awfully sad, but he felt better when I explained to him that I had no intention of ever hooking up with him, I was just curious. I was curious because before my husband came into the picture , XB was my first love.
So that could be what he was doing, was feeling curious.
Sounds like your H was feeling defensive because he got caught. I agree with T^2, be careful and be calm. However, and maybe people won't agree with me here, is I feel it's good to let it be known you're aware of what their doing. It could be a reminder of some priorities he needs to get in order. If the relationship is to be rebuilt, then it's important that you not bash him every chance you get. At the same time it's important he understand how the hurt and resentment will flare up with you at times too. It's a sticky wickett here I must say. You dont want to bash him, but at the same time your feelings are still raw and he needs to earn your trust back.
Please get into counseling if you can. Have you looked at marriagebuilders online? Wow that guy has many good articles about infidelity, and how it is for the spouse that strayed and the spouse that was betrayed. Once again, it all comes down to communication, listening and striving to understand.