"from the emails it seems like something is going on." Well, seems doesn't cut it in my book. If confronting without proof brings on denials and driving an A further underground (which no doubt it would),
The emails snippets you provided for us did not fit the it seems something is going on category, according to my definition of fidelity. I'm not blaming you for reacting slowly, but you doused yourself with water upon reading first email, when you should have been flaming mad and confronted!!!
That said, I still believe that you have enough proof to expose the A.
Whether or not WW thinks it is enough evidence to admit the A is her problem. You do not need her approval or agreement that she overstepped M boundaries and that you will no longer tolerate it.
I read someone's profile the other night, (sorry I can't remember whose it was) but they had all kinds of irrefutable evidence: PI photos, toll receipts, phone records that showed WS was in a different town 100's of miles away from where WS said they were, etc. WS denied all of it, to the end, even though it was all hard evidence.
At some point BS has to know what his/her boundaries are, what they consider infidelity and improper boundaries with OP.
BS has to be willing to get on with life if WS can't or won't confess to violating boundaries, vows, having an A (EA or PA, whatever...) and recommit 100% to repairing damage to M and emotional damage to BS.
You finally accepted WS is really having an A, and you are still in the early/obsession/info gathering stages. That's OK.
ShadowBoxer is right, to some degree. There does come a time when enough is enough (evidence gathering), and it varies from BS to BS. Give ChoppingOnions a bit more wiggle room to decide when he has enough evidence on his own.
If it had been me, I would have confronted with the very first email.
OM: Thanks for the document. Did you attach yourself to it? That would be great, so I can enjoy you!
WW: I wish I could attach myself. Keep an eye for a package in the mail.
OM: Are you coming in the package? P.S. This place is not as fun because you are not here.
WW: I wish. Good night.
Other emails I found discussing movies (including the quality of the sex scenes, nothing explicit though), overseas places he'd like to show her, and so on.
I know, I know, people are going to say that the A would have gone underground. But in my M, FWH would have never spoken that way with someone unless he was already becoming committed to leaving the M (Read my profile). His own conscience is what exposed the A. In his distorted mind, he thought that it would no longer be an A if he D me and M her. We're all different here on SI, and each BS has to consider their own M values and situation.
The next emails are strong evidence that the relationship had already become physical...no panties needed as evidence after reading the emails. Even if they were having phone sex and never touched each other, it is still sexual, and outside the boundaries of a M.
Then:
OM: YOU are the best!
WW: Your YOUs (in your message) turn me on in a big way.
OM: In what way?
WW: In the best possible way. Big smile. Good night.
OM: Please be more descriptive.
WW: Details: My breathing quickens. My temperature rises. My heartbeat rockets. The rest...for later.
OM: LOL! You are really something.
Finally:
WW: I am sad...I am patiently waiting for (our upcoming meeting overseas) so that I can get a big HUG.
OM: That's all you want?!
WW: I always knew you were a mind reader..I will think of more. A big sloppy X.
OM: I could say what I think about you!
WW: XXXXXXXXXXXXXXXXXXXX
ChoppingOnions. You don't have to wait for pantie results, but since you paid for it, and had already set your mind on waiting, just follow that plan if you have the patience,and don't go crazy waiting. If you decide you can't wait, the panties might come in useful later anyway to help WW defog.