I'm going to give a longer, and a bit more challenging, answer than I tend to on SI. If I remember correctly, you're an engineer (or something similar) so I'm going to go into some greater detail in my response, and directly address some of your statements. Please don't take this as a personal challenge to you, because it's not. We are, if nothing else, brothers in pain here.
This question is very interesting to me because of the following:
We dont practice what we preach. If I was giving advice to someone in my same exact situation, I would tell them to leave her ass and NEVER look back.
Well, that's the easy answer, at least, but easy isn't necessarily the best particularly when it comes to interpersonal relationships. I've dealt with friends' infidelities as well as my wife's, and I've never jumped straight to "kick the bum out."
Most of us, me included, wholeheartedly believe in the very logical "Once a cheater, always a cheater" life rule. Its a common sence rule, such as: Dont do drugs, Dont touch the oven because its hot, and so on...., yet here we are in LIMBO, in house separations, and on SI looking for advice on saving our marriages even though our marriages died long before D-day.
But we also need to acknowledge that such truisms are oversimplifications. "Don't do drugs" fails the first time you need to take antibiotics, or pain releivers, or take a No-Doze in the morning to wake up because the coffee-maker's broken. "Don't touch the oven because it's hot" isn't always true, it's quite possible for most adults to make quick adjustments to already-hot pans in the oven without needing protection (you might get a slight burn, true, but in my experience at least the pain's short lived and minor.) "Once a cheater, always a cheater" assumes a binary state of human experience and, further, allows us to delude ourselves that there's something fundamentally different between our essential nature and our wayward spouse's. Such an oversimplification implies that there exist two Platonic Ideals for humans: one Ideal that is 100% dedicated to a relationship, and one Ideal that is incapable of such dedication.
Things like that are, to use Terry Pratchett's term, "Lies-to-children." To quote Wikipedia, "Because life and its aspects can be extremely difficult to understand without experience, to present a full level of complexity to a student or child all at once can be overwhelming. Hence elementary explanations tend to be simple, concise, or simply "wrong" — but in a way that attempts to make the lesson more understandable. Sometimes the lesson can be qualified, for example by claiming "this isn't technically true, but it's easier to understand". In retrospect the first explanation may be easy to understand despite its inaccuracies, but it will later be replaced with a more sophisticated explanation which is closer to "the truth". This "tender introduction" concept is a common aspect of education.
Such statements are not usually intended as deceptions, and may, in fact, be true to a first approximation or within certain contexts. For example Newtonian mechanics is less accurate than the theory of relativity at high speeds and quantum mechanics on small scales, but it is still a valuable and valid approximation to those theories in many situations"
From what I learned, the BS never truly gets over the A.
I can't speak to the WS's experience, but only to my own. Your statement here is true, in one sense, but I think misstates the longer-term effects of an affair on the BS.
The affair and it's effects are, to me, much like a severe wound. One that's life-changing, but not necessarily life-destroying. Were I to lose an arm in a motorcycle accident, for example, my life would be forever altered. In that sense, I would "never truly get over the [accident]." But to take that as a suggestion that I would never regain a satisfactory quality of life would be a gross misstatement. I have been severely injured before: broken bones, severe and life-threatening cuts, I've even been stabbed in one eye. All of these injuries have left traces in scars, in impaired vision, in joints and bones that ache when the weather changes. They do not prey on my day-to-day life, they are simply bookmarks in the story of my life. Some of them are good bookmarks (the eye, if you'd believe it) and some of them are bad, and all of them were life-changing. But none of them have taken one bit of enjoyment of life away from me.
So, for me the choice to take back my wife wasn't one made from fear or weakness. It was made because:
1) It was what I wanted. Not needed, but wanted.
2) I knew that if my wife was less than honest, or if our reconcilliation didn't work out, that I and my kids would still be alright. That it would hurt, as the broken bones, cuts, and other wounds did, but that that hurt would heal in time and I would grow beyond it.
I'll have to come back to this, I've got some work to do.