I do not know your story but it seems to me you have lost respect for you wife and are not getting it back anytime soon. So tell me what do you even get out of this marriage? Do you find yourself thinking about other women/ Tempted by other women? I'm curious and not trying to be snarky.
To fully answer your question would take more time than I have to write and probably you have to read, but the short version is the typical drunken ONS on a girls only vacation. I trusted her too much and overlooked the selfish me, me, me red flags, and it bit me in the ass. I had been D'd before, and reconnected with someone from my hometown that had harbored a "thing" for me since grade school that I was only mildly aware of due to our age difference (5 years), which is nothing as adults, but wasn't even on my radar as a HS senior and she was 12. After what I had been through in prior relationships and now in my early 30's, it felt good to be the one pursued by the young hottie and it blinded me to the more selfish aspects of her personality, and as I said, it bit me.
I still, or maybe should say refound, respect for her, but she had to earn it back over the past nearly 10 years. My issue is more with the loss of the pride I once felt about our relationship that I considered "special", and after a lot of reflection, it is that "specialness" that I treasured so much, and still grieve its loss.
We have a very fulfilling relationship, and I know it gets thrown out a lot, but she really is my best friend. We travel very well and often together ... we spend hours and hours every week, just relaxing on our deck talking. We have a very satisfying and active sex life. We share a very active hobby together, breeding and training working bird dogs, and are the envy of most of our friends, who know nothing of our troubles, but that "specialness" pedestal that I once placed her on has been smashed beyond any repair. I also harbor some internal conflict over compromising my own values and only being able to confront the OM over the phone, since it was a ONS out of the country.
As for your last question, I work in a female dominated field, and am often cast in the role of their KISA, so I have a lot of opposite sex opportunity thrown my way and while I am human, and ego kibbles feel good every now and then, I've not been tempted to pursue them further, but I'm also 56 now and have matured greatly from some of my earlier days.
Hopefully, that answered a question or two, even though I wrote more than I originally intended.