I hadn't noticed that you came back to the boards. Wow! Lots of excitement at your house! I'm still caught up with the fact that she gave you a white scarf, and you left it in the closet, which she assigned a meaning to. Perhaps she thought you were surrendering? Only to find out that you hadn't surrendered at all, and she was the loser. Wow! Last time she gives her a rival a white scarf. People just don't know how to use them correctly.
Anyway, it's nice to hear from you. Sorry you are in this craziness, but it is good that he chooses you, not her. And whether he has a personality flaw that prevents him from being monogamous, I don't know. I suspect there are some people who are that way. But I also believe that people can change when they truly want to. But they have to really want to change.
I think the two of you would get a lot out of a Retrouvaille weekend. And, as soon as the holidays are over, they will be starting up again. Over the course of the weekend, it will become clear to your husband just how painful his affair has been for you. I'm not sure that you could ever communicate that message to him as well as they do.
Certainly, this all causes you to question your marriage. But it doesn't mean that it was all a lie. i agree with sg about keeping the good parts and building on them while getting rid of the parts that are rotten. Kind of like finding out your house is infested with termites.