You are correct; she is a scared, hurt, and confused little girl--deep down. Right now she's trying to justify her pain with poor behavior. No woman in her right state of mind would dismantle her family. So yes, she's being selfish and immature and there's nothing you can do to change her mind. Just like a toddler throwing temper tantrum...they have to come out of it on their own. The question is...how much/long are you willing to take this on? I know it's hard to detach when you're heart is invested but for the moment try not to put all your heart into it. It's counterintuitive, I know. When you know you're about to lose something you're natural tendency is hang on tight--almost out of desperation. When you do this it sends a negative signal to your W. Rather than sending the message of "I want you" it sends a message of "I need you." Wanting is showing desire, interest...etc. Whereas needing shows obligation. Who wants to feel obligated to love?
Continue to work on yourself and don't let your confidence diminish nor her petty attitude tarnish it. Don't show weakness but rather show vulnerability--it's sexy. Detach but don't be cold and unloving. I recommend reading "The Five Love Languages" by Gary Chapman. It will show you how to communicate love to her in a way that she will understand. Applying the principles might be difficult right now but at least you will be prepared.
In my sitch, my H is asking me to sign the separation papers and move out. The condo is in his name only but we have a new property being built which he intends to sell once it's complete. I'm a woman with two kids and currently unemployed since I have returned to school full time. Out of the blue he says he's done. Just like that my world was turned upside down. Of course WAS rarely ever give you the opportunity to make amends once you've realized where you went wrong. Sometimes, like for me it took him furnishing the papers before I snapped out of my funk. I did my best to apologize, appease, and all that crazy stuff. I've changed a lot and he noticed but he doesn't think it's genuine. Once a week I get pressured by him to sign the papers because he feels it is the only way he will feel whole again. It's a sly attempt to justify his leaving and running away from our problems. I've been faithful of course and I'm in great shape, smart, and funny but I have trust issues. He slap this in my face as often as he can to feel better about his lousy decision.
The sad truth, your wife is not in her right mind regardless of how happy, new, different she may seem. The fantasy of life with OM will eventually fade. Then reality will hit her in the face and give her a wake up call...slowly but surely. If you happen to still be around, lucky for her. If not...well sin has it's consequences. You may not be able to save your marriage but you will still be a better person for standing up for your beliefs.