I'm going to say some things. I mean them as gently as I can. I'm sometimes not good at gentle, though. I'm not trying to argue. I am trying to say what I see and offer to you some other ways to think.
Something people do is become invested in their ideas. It seems to me that you are very invested in your plan. Perhaps so invested that you can't see (or accept?) that there are other ways of doing things.
1) You're gathering more evidence. Why? You have all the evidence that you need to confront your wife with the _fact_ that she is having, at the very least, an Emotional Affair on her part with this other man.
2) Very gently, you're doing the right things (fixing you) for the wrong reasons (it seems like from reading your posts).
You are improving dancedad. That is hard, wonderful, marvelous, and your kids, your relationships with your kids, your relationships with others, will benefit from you improving you. Hard thing, congratulations!
You are improving you, so you said, to demonstrate to _her_ that you're "good enough." Now, I had this same problem back in my JFOs. The problem is is that you _are_ playing the "pick me" dance if you are changing you with hopes of changing her mind.
I understand because I did the same damned thing. The details are a bit different between our two cases -but- the desire was the same. You are (and I was) trying to control the outcome. You're trying to put her into the position of picking him (and unknown quantity) vs. picking you _over_ him. You are trying to get her to notice your improvements and choose her M and family over leaving for another man.
Instead, change you because you want to change for the better. Read up in The Healing Library, BS FAQ, item 11, The 180. The 180 _isn't_ to force her into a "pick dancedad" thing, though, it is to help you get some much-needed mental space so that you can make better decisions about whether you want a woman who has such poor boundaries that she _can_ fall in love with another man while she is still married to you.
There's another thing that is tripping you up, here. That is - this is all new to you, you're so few days out from DDay. She, on the other hand, has been withdrawing from you for some time. She's like, oh, six months ahead of you on separating mentally from a partner (you).
For her boundaries issue she needs to read "How to Help Your Spouse Heal from Your Affair", a book by Linda J MacDonald. There is a free one on her web site, you can add "PDF" to the title above and search for that and you should find the Mini-Books section of her web site. You should read it, too, to know what sort of things that you should be expecting from your W if she comes around.
Same web site, same section, the other free Mini-Book is something like "Who Will You Become?", which is a book asking Waywards exactly who they want to be when they grow up and act like adults. She should read this, again, if she ever comes around.
Another good book is an in-print book by Dr. Shirley Glass, "Not 'Just Friends'". This one is a really good book concerning "Just Friends" and Boundaries that people should have.
Something else to talk about is that all people develop things called "Mental Models" of everything and everyone that they interact with.
Examples:
My mental model of a snake is, "crawly round thing that gets all bitey and is poisonous." I stay away from snakes as a result. A herpetologist, OTOH, has a much more complete "snake" mental model and he knows which ones are non-poisonous and how to handle the poisonous ones.
A lot of people have a mental model of a car as "put gas in it and it goes. Every once in a while it makes horrible noises and off to the mechanic it goes." A mechanic, OTOH, has a much more complete mental model of drive shafts and crankshafts and camshafts and lifters and valves and suspension and... you get the idea.
Now for mental models of people. What we do is meet someone and, basically, judge whether or not we want to spend time around them based upon first impressions. We watch what they do and start building our model of the other person. When we haven't seen a particular action (like falling in love with someone else and cheating) we sort of paper over that hole in observations with how _we_ would act, or how we think that someone would act based upon how we feel about the other person. If we like the other person then we think that they'll act pretty well, if we don't like them the we usually assume that they'd be an ass.
Your mental model of your W did _not_ include the way that she got herself into her current situation. You're having the same problem as those folks in TV News interviews who say, "Little Billy would never set the orphanage on fire!" when Little Billy was found, a bit singed, with a gas can in his hand and matches in his pocket right outside the burning orphanage. And there were witnesses to him pouring the gas and lighting it. Also, pictures and film.
Tear down that mental model of your wife and start rebuilding it based upon her actions. Her actions are that she copes with problems by not talking about it, withdrawing from the other person, and then "falling in love" with someone else. She does this not to _solve_ problems, but to escape from them. Because either she assumes that working on it will be hard or because she simply can't envisage what working on it consists of. Irregardless, she solves problems by avoiding them and those are some horrendous coping skills that she's got going on there.
You, dancedad, want a particular outcome. You are invested in it. You are so very invested in it and how to get it that you're not willing to really consider other possible solutions.
You have enough evidence. You cannot control the outcome because your W is a free agent. She could decide tomorrow to just leave just like weeks ago she decided to distance herself from you and then convinced herself that you're such a monster that she just _has_to_ fall in love with someone else to solve her problems.
Frankly, dancedad, we've seen your approach before. Hell, I _used_ it before. It doesn't work.
The best advice that I can give you is that you sit her down and tell her what you know. Then you give her 24 hours to decide if she's all-in with you or not. As her H you have the right to expect that she is either all-in or all-out, not some sort of blameshifting, sitting on the fence bullshit while she figures out "her feelings". As a wife she shouldn't be having these feelings. That is _all_ on her.
So don't let her blameshift, don't let her deflect into "you invaded my privacy!", don't "give her time" or try a "trial separation" (which just gives her free time to mope over Pastor Bob). Tell her you know, you've got proof, and she's got 24 hours to decide if she wants to be committed to the vows that she took -or- she gets out, free to do whatever she pleases.
She's lost respect for you, dancedad. Frankly, the best way to get her to respect you (a man) is to be tough. Not hit-her tough, but take a stand and keep it tough.
EDITED
from She's lots respect to She's _lost_ respect. Bad typo, bad.
[This message edited by devotedman at 1:54 PM, June 26th, 2017 (Monday)]