Keep snooping. Truth is the truth, you need to know it. You can't work in a fantisy world and make good choices.
I think you should be careful with that. I guess it depends on how you react to new info. I for one had to stop. If I found out anything new that upset me it made it very hard not to confront her with it and in turn was making me miserable. By showing these emotions it pushes her further away from me. I told my W about how I found out so that it would force me to stop. I already know enough so now I just focus on improving me.
I will admit that I still check the caller id list from time to time as that doesn't drive me crazy, but that's it. Just proceed with caution if you snoop anymore.