thank you in advance. A potted summary of my situation:
(a) we have been together 26 years, married 20 (this year), one daughter. We are still "soulmates" (which makes everything so hard to compute)
(b) as I read it, at staff Christmas party my wife is informed by a senior manager that he fancies her (she is a good listener and misread his closeness previously). After the initial shock she becomes flattered and then crosses the line (we've had a good conversation about this). I discover by accident over New Year what's going on (was expecting a Whatsapp photo on her phone, what I got instead was a long list of intimate messages.
(c) had it out with her (more than once). All very calm and amicable although she naturally played down her side of the equation (yes he is a nice guy, yes she was flattered, he is very lonely).
(d) I am afraid I have been reading her texts (not recommended I know) not out of paranoia or stalking but just to gauge the level of what appears to be quite a deep emotional affair. My wife has high morals (!) in that it would not go to the next stage (it is a work thing with no potential opportunities outside of that).
(e) here is the rub. After our main "conversation" she said we should have a fresh start. Ever since then (and believe me I know when she is being insincere) we have become closer than ever. The physical side has also increased (I appreciate there could be various reasons for this but again this is definitely heartfelt).
(f) the EA is heavy and still going on yet everything is so "normal" here. I just don't get it, we are getting on so well.

So is she compartmentalising (classic EA behavour, "not doing anything wrong" in her mind as it hasn't gone up to the next level, etc.).

thank you again