Yeah, I was pretty pissed. Thankfully I didn't actually DO any of the things I fantasized about to 'get even' - now that we're back together it might have been a bit awkward

He knows how I felt though. I once asked him if he could guess which song was my 'theme song' for a few months after D day - he said 'Next Time He Cheats' by Carrie Underwood, which was close, but it was actually 'I Pray For You' by Jaron and The Long Road to Love. It's awesome. After the first minute - watch it on youtube.
Anyway, yeah, I can be quite childish
I printed everything from the computer - his pics, sexsearch and aff profiles, emails, everything. I still have them too. One of these days I will be ready to get rid of everything. I have all the emails I found saved, although it's been a few months since I looked at them. I hacked into his secret email accounts and just recently deleted those, as well as his facebook account. (this is with his knowledge and blessing) SO I am slowly able to let go of these things, I don't need to keep analyzing them like I did at first.
One thing I found quite helpful was to write a timeline of events based on what he told me and what I knew. Because I was one of those BS's who asked the same questions a hundred times before I could let them go. I would check and make sure his answer hadn't changed from one asking to the next, and when it didn't I felt better and was able to move a teeny bit farther down the road toward recovery.