Mitch, I recall going through a phase where I kept apologizing to my wife as she kept preparing to leave and partying with her friends on weekends to "make herself feel better". I think you're going through he same thing.

Let's say you were indeed the horrible husband you think you are. There's a pile of options for her to take...she chose cheating and sexually humiliating you. That's one of the worst choices, would have been more respectful just to leave.

Take heart, you aren't a horrible person and you deserved none of this.