It's all in how you look at things. I am having the same exact feelings about my W right now. Fact is that both our W's had sex with other people before us. What bothers us is the whole possession thing. I know you maybe didn't meant sloppy seconds quite that literally but either way, if she comes back to you, you will not be the second, he was. Sure, could she just run again? Yes. There is no easy way around that. Could you also see your part in this and work towards being better for you first, but also better in you M, and to your W? Look, we all have these feelings like "why the hell should I be doing all this work when she's the one cheating on me, ready to walk away from me." It's the natural reaction. Problem is that like temporary insanity in a criminal trial, our W's can claim that now. They are not right. They may never BE right again, or maybe they will. If we don't work on us, to be the best we can be EITHER way, we'll not be there if and when they decide to accept their part in all this. I can't promise you anything, but I can tell you it has helped me a lot (not that is shows right now) and I would suggest reading the books again ASAP. We are all trying to help here but we are no experts. It may be helpful to read what a true expert is saying.