Scared... Your situation is very similar to mine. The comments made by your wife are exactly what my wife has told me. I would be very concerned about the potential of OM. My wife initially denied the existence of OM and told me the same things your wife has said.
It just didn't add up in my mind and I paid close attention to what she was up to. Turns out she was/is having an EA with a co-worker. Although there was nothing going after hours etc, there were lots of lunches, coffee breaks, texting and email messages.
The basis for all of her actions and behaviour became crystal clear once I confirmed the EA. I never thought my wife would be the type of person to cheat. When the bomb was dropped, I asked her about another man and she said she would never do that.
I am not saying that your wife is involved with someone else, but I wouldn't be too quick to rule it out.
