Every situation is so different.
My XH had more than he could even try to count (Mostly prostitutes but not all of them were).
My current H has been intimate with 5 women in his 57 years, three of whom he married (I'm obviously #3). He cheated on two of his wives (#1 and #3) but with the same whore! I wish I knew more about the circumstances during his first M but his memory is poor and I just know I am never going to get any more facts than I already have.
As time has played out, I have had to draw my own conclusions based on what he did tell me and other things I have been able to discover. I don't think my H held a candle for this whore all those years though it certainly was a question that came to mind when she first intruded our M, and I knew about the "history" 25 years prior.
It seems more likely (in our case) that this whore did tell herself she was "in love" with him all through those years and he was flattered by that when she informed him of it, and during a particularly low time in our lives following the deaths of his mother and DD and other things, he allowed himself to get caught up in the ego stroking as a temporary way to feel better.
Runninggirl, sounds like your D-day was around the same time as mine in 2006. My H expresses nothing but disgust over the whore if there is ever any reference to her. I feel for you with your H acting this way again.
All I can say is that after what we went through 7 years ago, if my H showed one ounce of concern or sense of flattery over anything that whore might do now or in the future, I would immediately file for a D. (I'm not suggesting anybody should do what I would do; we all have to decide how to live our own lives). And I did inform the Whore's H and I'm very glad I did.