pookie throughout your posts, you keep mentioning "WTF" as if you don't understand? You aren't that clueless. She does those things because..... she feels..... guilty.

Now you know who the OM is.

That is money in the bank.

Go to him.

Speak to him like a calm man,
don't go over there with a louisville slugger (real wood not the titanium aluminum alloy) and do some weird outer space stuff where you put him into orbit.

Ask him with a smile on your face:

"Did you enjoy your dinner last night?
I hope you did, really I do, they make a fantastic <insert name of favorite dish>, it really is so.... CHOICE.
Anywho.... spoke to the wife, confirm you guys went out,
I want you to know.... I'm happy for the both of you,
you can have her now because I don't want her. One last thing though, does your WIFE know about this? NO? She doesn't?
Well I hope I don't interrupt your family dinner plans tonight, I'm just going over there right now to have a chat with her about the current state of affairs between you and my wife. My plan is this, you can have my wife, I'll let your wife know about what you're doing, so that she can tell you the same thing."

Smile, shake his hand, walk away and inform Mrs.Z

- maybe ask her what her plans for dinner are,
ask her out to the same restaurant, see if she has her husband's credit cards on her, I hear that restaurant has an excellent wine selection ;-)

LOL!

Cue the NIKE commercial..... JUST DO IT!