I'd be surprised if most WAS were happy and confident. I'm not. I am determined though.
I've been down this road before with my H, except last time he wanted the D. I was embarrassed and ashamed and hurt. I don't know how I got over the embarrassment. I guess it just took time and acceptance that I was going to be divorced. I realized no one would think I'd somehow intentionally wasted there time and energy celebrating a relationship that didn't last. As for anyone who might snicker behind my back or grouse for whatever reason, that would make them mean, not me.
H never cheated on me, but I remember the humiliation of being cheated on by a boyfriend. Oh, I was furious. In my case, no one but my boyfriend and the girl he cheated with knew about it, but the idea that this OW knew was still sickening. There isn't a cure for that, but time.
When I dropped the D bomb on H last week, I was really sad. I wanted so badly for my H to come back and be the knight in shining armor that he used to be and tell me everything would be okay. And that would be a pipe dream... in my case H tells me everything will be okay on a regular basis and then turns right around and behaves badly again.
You obviously don't accept an open marriage and in that case can't accept OW in his life. (Surprisingly, some people can.) That being the case, it's okay to walk away with your head held high. Just work on yourself, be the best person you can be, and don't worry about what he's doing. He needs to take care of his own problems.