You have been doing the right thing by giving her the space she needs to figure things out. I like the fact that you are not discussing the relationship/marriage w/her and allowing her to bring it up. As you can see, the less pressure you put on her, the more she settles down and communicates better with you.
She's feeling some guilt and possibly shame for what she's doing, but I suspect that something transpired on her trip that sent her into a tailspin. Maybe she works with the OM or met him while away and he stroked her ego just enough to have her question herself and her life. Whatever transpired, she's searching for that illusive happiness that she thinks that is out there...but it's not...happiness comes from within.
Continue giving her the space. Try to keep your conversations casual and on topics such as your children. For now, treat her as you would a friend. Keep the focus on you and your children and one last thing...dig deeper for patience. This is now a marathon, not a sprint.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
