Yes, 2x4s... but you know what you did was wrong...
Or was it...?
Why did you look? After so long of suspecting, why did you look?
It is said about "cheating"... "If you don't know if you are cheating, just ask your spouse..."
If they are keeping a certain something quiet... if they are hiding someone... and withholding is a form of lying... they have a sense that what they are doing is "wrong"...
So, back to the question... Why did you look?
But... you looked... what did you learn? You learned that your gut was at least close to correct... there's something more about this guy than she's telling you... so why do you feel bad about finding more proof?
How does this change your stand? What is your fear around "knowing" she's cheating...?