Phew - now you're all safely snuggled down ...
My first marriage was a farrago, I now realise. So the judgements I made were made on a backdrop of crap family relarionships & crap expectations. I didn't realise that at the time, and this is why I'm trying to review such questions now - much older, and a little bit wiser.
We were both v.successful and had exciting lives, together & separately. He was hopelessly unfaithful. Opportunities were rife. I want to talk about one, single class of opportunity: he was often entertained, by large corporations, in various different countries. The hospitality often included a naked girl in his room. When he got home, he would tell me this. I'd ask a few questions, basically of the "oh how interesting, do tell more" variety. I absolutely didn't want to know anything about the sex - and instructed him, very clearly, not to tell me even if I was having an insecure moment & asked! It bothered me, but not in a huge way - more like the way I'd be bothered if he'd been to dinner at a restaurant I wanted to visit, or to a gig I would have loved.
These trips were usually 3 or 4 days. Even if the girl was in his room every night (unlikely), he wasn't going to see her again or form a relationship with her. They were designer hookers.
In my job, I was offered enjoyable inducements but they never included pre-paid sex, so there's no direct comparison. I did cheat on him once, with a well-known (at the time) musician after a work do. Our row, the next morning, went something like this:
"Where the hell were you? I was trying to ring you!"
"Ummm, I got drunk and slept with the drummer."
"??!!&&%%!!"
"I know. I'm sorry. How can I make it up to you?"
And that was it.
Now. He was also unfaithful under other circumstances, and that is why I finally quit. His [not pre-paid] infidelities involved lying & fudging, and I hated it. It made me feel disempowered. Ours was a horribly unequal relationship - the sort that would have us all (myself included!) urging the OP to step back & see what was happening to her. So I can't adopt anything I did, then, as a model for my present life.
I can't say, either, that I'd be any less laid back about the designer hooker sex. It cost us nothing in terms of money or emotional connection. There was no danger of repercussions. There was no dishonesty.
As I say, I really don't know how I'd feel about it now or in the future. But I do feel there was sound logic in my attitude then. Unfortunately, I suspect my attitude led him to feel it was OK to cheat otherwise, as well!