You are doing great!
When it comes to the confrontation, honestly, they are so skewed in their thinking that no amount of evidence is truly “enough”.
I literally caught my husband and his mistress naked in our bed and he still tried to deny that anything was going on, and actually tried to shout me down and say that I was crazy.
Assertiveness is key for you!
Do not ever pose any of your accusations as questions.
For example, say, “I know you have been making calls to AP and deleting them from your call log.” You don’t have pictures of her phone from every time you saw that the call logs from her phone and the phone records weren’t matching up, but that doesn’t matter! You saw what you saw, and you know what you know.
When she says “You’re crazy, you don’t know what you’re talking about,” you say “I saw it with my own eyes, and there is nothing you can say to convince me that the truth is not the truth. You have two choices, admit to it, or deny it. But remember, I am not guessing or speculating. I know these things to be true.”
“I know” statements are your ally here. No hemming or hawing, no matter how much she tries to spin it.
If you stay calm, it is easier. My STBXH went off the rails when I confronted. But when he kept trying to say I was crazy and that it wasn’t what it looked like, I took deep breaths and responded very calmly.
All that said, if you can put a GPS tracker on her car I would. If you’re worried about her bringing it up legally, put one on your own car too and say you had done it for safety purposes to keep track of where everyone is. If you can confirm that she is going to a hotel when they are supposed to be “training” that will be the nail in the coffin for you.
Or even if they are going to his house, and the OBS can confirm that those are times when she was not there, or when her own spouse was saying he was somewhere else, she can corroborate for you.
And you don’t ever even need to reveal HOW you know that she wasn’t where she said she was. Usually if you just keep repeating I know statements, and you don’t give in, even a little bit, they will eventually have to concede. It’s amazing the power you have when you look them in the eye and just keep repeating “I know...” no matter what they say.
They get scared, because they don’t know how you know, so they don’t know how to deflect or spin it. The least amount of information you give them the better. The more details they have, even if they are small, the more they have to grasp at and try to spin it that you are the crazy one.
Before you confront, really consider how you will 180. You can’t technically kick her out of the house. But you CAN move all of her things out of your bedroom and into bags/boxes while she’s at work, then put them in the garage before you confront. If she chooses to leave the house after that, then you have not kicked her out, she chose to leave. If she won’t leave, you can always say that you will not tolerate her being in the room with you, and she can stay in the spare bedroom.
Also, don’t ever forget that she KNOWS this is wrong, and she chose to do it anyway. The fact that they created a secret email address to communicate with one another really says it all. If everything was above board there would be no reason to hide it.
Get yourself some sleep before you make any major decisions. You have the benefit of knowing quite a lot, and you haven’t blown any of it up yet so you have the element of surprise in your favor. Plan, plan, plan.
Remember that the second you confront, she will go on a deleting rampage to try to cover everything up, so take pictures of everything. If you can, before you confront, get her phone back one last time and take screenshots of every little thing that seems off. Then text them to yourself and delete those texts from the chain in her phone.
And yes, all property is marital property, so transferring out half of the $ into your own account should not be a problem at all. But always consult a lawyer just to be sure of your rights.