Dinged,
As I see it, I think you've got TWO things going on here that need to be addressed separately.
First, or rather most recently, you have been confronted by what your wife is doing sexually with her boyfriend. You find their sexual tastes and proclivities disgusting. However, I believe that is not the issue you need to deal with. However reprehensible you find their behavior, keep in mind that many people get into polyamory because of a difference in sexual desires and tastes. If one partner feels a need to be kinky in order to be sexually satisfied, while the other does not, an additional partner can fulfill that need (if there is an agreement to open up the relationship). Kinkiness, in and of itself, is not necessarily sick and the people who participate in it are not necessarily pigs. You see it that way because it is obviously as far from your reality of what sex should be as it could possibly go. But what she does with him has nothing to do with you. The fact that she seemingly let herself get "caught" is more related to the second issue, that you need to deal with.
I understand it is painful for you to see those images of her doing something that disgusts you so much, and of course for your daughter to have seen them, but I think you really need to separate the acts themselves from the larger issues that have been brewing all along. Try to set what they do aside for now. Because, hypothetically, let's say that if you two healed everything else that was going on between you, like the lies and feeling like you weren't getting enough attention, as an example, you may have come to a place where you were okay with polyamory. There might have been a point at which you accepted it and felt okay with her having a lover, and you might even have chosen to have a lover too. And, if that were the case and you had never found out what she was doing with him, you wouldn't be cringing about it -- you would just be focused on your relationship with her, not her relationship with him.
Many poly couples don't share what goes on intimately with their partners. For many people, they just don't want to picture anything, so this is not unusual - but healthy relationships can still be had between a couple, even if one of them goes off and does some wild shit with their other partner. So, again, I think it would behoove you to try and set aside that aspect of what's been happening, because her sexual expression with him is not as relevant to your relationship as much as how she has related to you.
So, here's the second and most important issue: you've been struggling with your relationship with your wife for a while now. Your first post here, back in January, stated that "about 7-8 months I was reluctantly pushed into this lifestyle." That statement right there means that you didn't want to be in a poly situation and were essentially coerced into going along with it. Red flag!
Now, I'm sure there's more, but I am going by the threads you've posted here. Your wife and her boyfriend had a few strange encounters with you in public and you felt like he was trying to get the scoop on you while you didn't know much about him. So, there was a little weirdness, your wife didn't try to make meeting him an easy thing for you. It seems she can be very selfish and uncaring. So, you set certain rules to be followed: they don't fuck in your house, they must take precautions so that your wife doesn't bring home "so much as a fucking cold" (your words), and nobody touches your car. All reasonable.
Last month, you wrote about feeling like your wife was not focused enough on you and the family, that you didn't feel special to her, and that you and the kids weren't getting enough of her attention. You mentioned wanting her to feel as dissed as you did, a little vengefulness on your part, but you also said, "I have started to moved toward being open to the possibility of dating and or relationships." So, you've had some uncertainty and ambivalence throughout, and she did not seem willing to make changes or compromises to accommodate your feelings.
You feel hurt and have resentments but you tried to accept this other relationship of hers and prepare yourself for the future. You've talked about wanting to step back from being her primary, about her making good money and never contributing, and about no longer wearing your wedding band. You're trying to hash things out and then your wife decides at the last minute not to go on a family ski trip you had planned. You didn't protest, although you didn't like the fact that she didn't want to go. You kept silent and stewed about it. Then you wind up in a car crash with broken ribs, and when your daughter calls her mother you all find out she's in Vegas with her lover and hadn't told you she'd be there. The two of you clearly have problems involving trust and honesty. You said you also think she's trying to fill up some feeling of lack within herself. From what you have related here, there clearly seems to be a lack of communication between you and some disrespect.
While, yes, she has not behaved forthrightly, it seems you don't express your anger and then you do something to get back at her -- like changing your insurance policy without discussing it first. You've both tried counseling, but apparently not for very long and nothing was truly resolved. You have said you won't walk away, but underneath everything, you have been seething.
Now this happens -- pictures are found and it's like Vesuvius has erupted. Can you see how some of the rage you're feeling now has been bottled up for some time? You two have very fundamental relationship issues to work on; it isn't just about some kinky pictures. It's possible your wife tried to get caught as a "plea for help." She may be a sexual compulsive or have some deeper psychological problems, or she might just be tired of trying to hold it all together. She could have been feeling like her life was spiraling out of control and she needed to cry out in some way -- who knows? Yes, she seems like she has abandoned her responsibilities and is acting rather crazy. But don't let your reaction to the kinky stuff and the emails color what needs to be done to deal with the underlying problems between the two of you.
You have let your needs be swept aside and not expressed all the hurt and anger you've felt about it. In the midst of taking care of your daughter, also take care of yourself. Forget about revenge - it will feel like a hollow victory and send you deeper into despair. Focus on HEALING. It may mean divorce, it may mean reconciliation, it may mean communicating, it may mean lots and lots of therapy for both of you or the whole family, or any number of things -- but be careful with how you react. Don't let the content of the pictures sway you from what is underneath all the stuff that needs addressing. What's in the pictures have nothing to do with it, but being careless so they could be found seems an obvious statement, or a symptom of something much deeper. You are both in pain, and I suspect there's been pain for a long time.
I hope this all makes sense, and I wish you strength and healing.