These were my thoughts from just now reading your first post on this thread and they haven't changed since your followups:
First of all, I would be OUT OF THERE from the beginning. What I mean is, you have to understand that this relationship is over.
This is probably as good a place as any to get good relationship advice (because as I've come to learn the people here are VERY insightful -- seriously, understanding how to work poly relationships must involve attaining a relationship counseling degree of sorts) but I don't think there's any polyamory happening in your (ex)relationship, and would be just as well floated at a conventional relationship message board. I understand she said some words about polyamory at the beginning, but THE WAY SHE ACTED WAS SELFISH and NOT in line with a polyamorous relationship. You WERE swingers. I don't think either of you seem to be polyamorous-natured. Not saying you shouldn't consider it, if once you have worked all this out you feel it does resonate with you, and you don't have too tainted an opinion of it as a result of your wife's abuse of the term.
I'll echo what above posters have said. HONESTY is the MOST important thing in making ANY relationship work I actually believe it's important in all aspects of life, people are just too dishonest with each other in general. I believe lying to your friends or people you love is wrong (I lie to my parents about some things, but that is my only exception and that sounds terrible but there are certain lifestyle decisions of mine that I know they are vehemently opposed to).
From what you said, that she would spend the night with "that fucker" and not have sex with you, she wasn't meeting your needs. You should have known right then that you would have to leave her. I think she was TRYING to get you to leave her so she wouldn't feel like the bad one, like YOU were the one who just wasn't understanding.
I AM of the mind that you weren't understanding, because you actually thought you could make the broken relationship work when she was making no effort to fix it.
I'm sorry if I'm offending you in my tone or message, I just want you to really see how terribly you were being treated and how pointless it is to try to remain in a relationship with someone acting as selfishly as she was.
You don't deserve that. No one does.
From your first or second post, there was one thing that stood out to me as a reason why MAYBE, POSSIBLY you were still trying to make it work after your treatment: your two kids. I would think if she had been honest from you from the beginning, a marriage of convenience might have been workable, where the two of you stay together on paper and maybe live in the same house part of the time to raise the kids. But as a result of her dishonesty and unreliability, I really think the best thing is for you to get out of there and fight for the kids if you want the best for them, because I don't know the situation, but I don't think your wife will be trustworthy.
I wish you the best of luck.