I appreciate where you’re coming from P&C, but I have some concerns for you.
First of all, it’s not clear that you actually love her. Most people here believe that staying in a M for the kids does more harm than good when there’s infidelity in the mix.
Secondly, you don’t really have any evidence. Listen, I believe you. I am big on "trust your gut" when it comes to this stuff. You’ve got plenty of smoke, but no actual fire. You know she’s cheating, and we believe you.
But you don’t have much in the way of evidence. And human nature is what it is. Cheaters follow a pattern of behavior so predicable that on this site it’s called the "Cheater’s Handbook", as if they were all reading from the same instruction manual. So if you confront her with I heard some sexual jokes and the sexy nightie in the luggage, she is just going to deny it.
There’s a woman posting on JFO right now who literally found love notes from her WH’s AP, and he’s still swearing it’s nothing. People here have denied actual smoking guns, sworn on the immortal souls of their children.
You’ll say, "WW, I know about you and Boss. For the sake of our DS, I’d like to try to rebuild our M, but to do that, you need to come clean." What do you think she’s going to say? If history’s any guide, she’s going to deny it. Hell, in your first post you said you’ve gotten 10 years of gaslighting, partial disclosures and denials. Hard to imagine a different result now…
I think you should consult an attorney first. Can you hire a PI? Get access to her devices?
I hope others can chime in with suggestions, but if you want to confront with what you have now, I think your message is "I know you’ve been having an A with Boss, and I’m speaking with an attorney."
There are tricks people have used in the past like hiding a VAR in her car, so that after the confrontation if she hops in the car and calls her Boss you can hear what she says. But other than things like that, you don’t have to say much more - if she wants to save the M, you can assess that from her actions (like going NC with her Boss and quitting her job, e.g.).