Go --
Hard to keep up with you; you move around so often (lol!). But I've found you here in GQII, so we'll use this Forum for awhile.
One of the things I've learned in my time here at MB is that posters often answer their own questions, sometimes inadvertantly, but clearly and correctly nonetheless. You now have accomplished this valuable feat. You do in fact have "proof" of H's involvement with OW. I've borrowed from your other post...ready? "he does not love me, that his feelings for me are gone and that they are not coming back. Oh yes, he also says that he questions whether we ever had a connection." = All classic, textbook, Fog-generated statements from WS to you!
Countless numbers of us (myself included!) have heard these exact same words and for the exact same reasons. An A is in progress, sorry to say. Believe it or not, WS's follow virtually identical scripts when discussing their behaviors with BS's, varying only in timing, but never in content.
You went on to say, "He still will not admit having any relationship with this other woman or that she has anything to do with this." -- read this again and you'll see the obvious non sequitur. "There is no other woman...oh, and she doesn't have anything to do with my feelings." -- more Fog-bound nonsense. Please find WAT's marvelous "Quick Start Guidelines For Betrayed Spouses" in the JFO Forum. It's all there. Everything you need to know and what to expect.
When confronted, most every WS claims no A at all or "we're just friends" so we learn nothing concrete, but the doubts and feelings don't go away = your case. You have your instincts because you know your H and you know something's amiss. Keep snooping (here called Basic Research), keep your eyes open and your instincts sharpened. Trust your gut. I have no proof for you but I've spent a lot of time on this board, enough to "smell a rat" when it's described to me. If an A is in fact on-going, something will emerge to confirm your suspicions. I think a gentle talk with H is imperative. Let him know (even though "nothing's going on") that you're immensely uncomfortable with your feelings.
I hope very much for your sake that this isn't the case. I wish you didn't have to post here and share your fears with us. Let's both hope these fears aren't confirmed. We're here for you...
Ammon