Your last thread had a lot of debate about snooping/exposing etc. Different sites give diametrically opposed advice about this. My advice is that it depends on your goals and your situation. Your situation is that you have a WW who is actively in an affair, it is not exposed, she is in the process of divorcing you. And, based on her outrageous behavior towards you, you can be certain she will do everything she can to destroy you in the divorce.
So I think your actions need to be focused solely on protecting yourself and your children emotionally and financially. Right now you need to stop thinking about saving your marriage because, frankly, it is not up to you. It is up to your WW because she has already decided to file, so she would need to be the one to decide to stop it.
First, go in for consultations with at least 3 attorneys. Dont get the cheapest, and pick the one who seems most experienced with fathers rights and knows about the potential judges. You dont need to retain them right away, but these meetings will answer many of your questions and will greatly reduce your fear and anxiety of the unknowns, which is usually the scariest part of this.
Second, determine if adultery will have any bearing on the divorce proceedings. This depends on your state, and your judge. Some states disallow alimony after an affair. Some judges even in no fault state will come down hard on a cheater during property division and custody. And sometimes, whether a state is 'at fault' or 'no fault', cheating doesnt matter at all. If cheating would hurt her in a divorce proceeding, then snoop away but hire a PI so you can get court-approved evidence. Even court approved evidence will often be dismissed if you do it yourself, and you open yourself to ROs, thus my advice on a PI.
Third, if you are not using her affair as divorce evidence, then decide how you want to use it to your advantage. By this, I mean you can blow it up, there are some ideas above, but usually a call to OM's wife and their boss does the trick. She will hate you at first, then maybe she will run back to you later since you are still probably her backup plan. Or, you can use it as leverage against her. She can stop disrespecting you, leave and divorce quietly, or everyone finds out. This is where you can use non-court approved evidence. Or, third option is just to let it be common knowledge, not as exposure to try to blow up the affair, but just so that your WW can't continue her charade of pinning everything on you. And trust me, right now that is exactly what she is doing. And this approach ties right into my last piece of advice -
Fourth, be honest. Unless you are strategically using her affair as leverage, then dont keep her secret, especially from your kids. I know first hand that teenagers do not deal well with crazy behavior by their parents that they cannot understand, and will almost always assume fault themselves. I always, always advise parents to be completely honest with their kids about the changes and causes of change in their lives in an age-appropriate way. Just telling them 'its fine, its fine' is lying to them, its not fine, and this is doing them no favors. They need one parent they can trust. Sure, it will rock the boat, but that will be your WW's problem to address her relationship with them. But when these earth shattering secrets are hidden from kids - thats when I have seen these kids end up with permanent emotional scars.
Im sorry you and your family are in such a terrible situation - good luck!