I see a lot of discussion about forgiving her for dating an other man and being physical. And I don't get it. I read the part about what a he!! her life was at home, and all I could think was, "Wow! What took her so long?"

Yes, you need to forgive her for what she did (reactionary and self-preservationary, as it was). But I just don't see you particularly worrying about how you are going to be sure that you offer her a better marriage to return to. Do you worry that she might not forgive you? That she may not ever be able to trust you not to get angry and fall into the ugly old you? How are you going to build that trust? How are you going to rebuild the commitment? Seems to me, you have the easy part in forgiving her a sexual transgression. She has to forgive an entire personality transgression.