She is going to say she didn't. You'll probably never know for sure. It's not what is most important. I know a marriage the survived infidelity. Became a good and stronger marriage afterwards. Your marriage has way bigger problems. Your wife has profound damage in her whole mindset. This was due to influences that go way back before you even met her. Something was wrong in her parents' marriage. Something about the home she grew up in stunted her development. The needle on her compass is broke. You have a concept of what you think a marriage should be. Your idea if marriage may be a bit rigid and rather idealistic, but she doesn't even have a concept. She has no idea what she believes in.

Try to consider that she may not be capable of having the level of integrity that you feel a spouse should have. Somewhere along the line she never had certain values instilled in her. She's trying to create a value system for herself, and she is starting from scratch. She's like someone wild in the woods - a feral creature - trying to reinvent the wheel. She's like a primitive human trying to figure out what it took civilizations thousands of years to figure out. Her future isn't very pretty. Someday, I'll bet, you'll find yourself feeling pretty sorry for her, regardless of what you do. It feels to you like she has all the power right now. Her aporoach to life is not how anyone builds secure self-confidence and independence. You getting mad isn't going to phase her in the least. She doubts all the basic things that most people feel sure of. She's probably not going to live long enough to figure it all out. She's thrown off constraints and is conducting a big cynical experiment in "Let's see what I can get away with." She feels self-empowered by this. This is, basically, an amoral approach to life. I'm not judging her because she might have had a sexual fling. That's nowheres near the big deal that you think it is. She has no scruples. That's the big deal. She honestly thinks scruples are for suckers. That's why I say she has a streak of the sociopath in her. It's probably not her fault. You have to look at how she grew up. Something was very wrong.

You can move on. Your kids, however, are stuck with her. They don't seem to trust her either. You have to try and keep them from being damaged by her patterns. So you need a cooler head and less outrage that your manhood was insulted. Berating her is a waste of time. Her moral compass is different from yours. Her needle is broken. She knows it's different from what people generally believe. That's why she wants nothing to do with counseling. She thinks life is a game where first prize goes to whoever can be the trickiest. That's not how life works. But she wasn't taught right.