I think Starsky's advice is going to get you the most traction here. He's succeeded. That's saying alot.
I did not save my marriage. All I can do is share my mistakes.
Couple of things re: snooping.
Your wife has demonstrated herself to lie and even try to do so in the face of clear evidence. She's done this repeatedly. So actually believing anything she says (that the affair ended) is pretty foolish. The ONLY way you're going to know she's ended it is by snooping. Sorry, dude.
The point that snooping only upsets you is partially true. It will drive you nuts. But, on the other hand, she can't be trusted at this point to tell the truth.
Regarding the dating site. Quite simple: She's interested in dating other men. She's cheating on you know, and she's taking steps to continue cheating on you. Or, she can just be curious to see if she can do better than the OM. She's not playing mind games -- she's pretty openly narcissistic at this point.
Re: the pleasant times together. My ex was sleeping with me and the OM (when I didn't know they were having an affair). She enjoyed stability with me and the romance with the OM. She was waiting for OM to leave his wife so that she could divorce me and run off with him. In the meantime, she was quite happy to have 2 men in her life. Cake-eating.
I have a question: On the socio-economic scale (income/job/status). Where do you, your wife and the OM stand? I sounds like she makes more money than the OM.
Look. She knows you know and is still trying to lie to you. At some point you are going to need a plan. You can't sit in limbo trying to "get-a-life" and out-nice the OM forever.
Even in classic divorce-busting there is the LRT, After the Last Resort Technique and Ultimatums.
My concern is you will drag this on too long and she'll lose attraction for you. Make a plan and stick with it. With a time-frame. I think Starsky can help.
Also for a completely different (and humorous) take on infidelity -- visit the site Chump Lady.
