So my question is what does this have to do with you being a man or woman being betrayed and being told that sex with the AP is better than with the BS...
I really has nothing to do with being either a BH or a BW; it just often seems that way because of the things that each sex seems to value, on average, more than the other.
I was devastated and destroyed when I was told that especially since she was half my age and never had a child. He apparently had ED with me but had no problem getting it up for her
FYI- TMI ”shot his rod the minute he penetrated her because she was soooo tight”
And this is a great summary of the "plan A" stuff, can't get hard with me, can't make it 2 pumps with the AP.. It seems hard to talk through that and still come out of it feeling like plan A (sexually). And while that particular issue isn't a problem for me, the general thing that you're feeling there is. No desire for me (can't get hard), can't keep clothes on around AP (can't make it 30 seconds into sex before orgasm). And now take that issue and project it to someone who was starving for sex in their M and puts a very high value on sex generally (which may be you, no projection necessary, but that's also me and many of the BH's who post on this issue; high drive, high value placed on their sexuality with a partner who "can't get it up" for them but is who's "prematurely orgasming" with the AP.
Which is why him telling me that really fucked me up and made me hate sex with him because of the constant comparison in my head.
It hasn't made me hate sex, but I do totally understand where you're coming from. It's made sex less enjoyable than it used to be, that part is true for me. But it's not the constant comparison that really gets me, it's her actions that can (or can not) show me that I'm her first choice. Now I look for evidence that I'm the "first choice" all the time in bed, and before, I never did. I assumed "She just had ED issues" and accepted it. But, like you, it turns out those "ED issues" were entirely related to me, and not an actual difficulty with bloodflow or desire. Just desire for me.
He later told me he just said those things in anger and it wasn’t true..., hahahaha not that stupid because we know there’s truth behind it.
And this final one, yes, this is also a great description of how I feel. "We know there's truth behind it" is really the crux of it. Sure, you can tell me all day long the sex was "nothing special" and not the reason you were in the A. But, the "truth" tells something different. In your case, the erections and premature orgasms tell a very different story than "nothing special". And in my case, the sheer frequency and acts my W did in the A tell that same, very different, story.
While others disagree with me, I do think that this issue is unique between the sexes in a lot of respects. And, as much as it might surprise you, I think, if anything, a lot of this would be harder for women than men. Painting with a broad brush here, but "new sex" seems to range, for lots of women, between "awful" and "just OK". It seems to take a lot more time for women to get to the "happy place" sexually with another man than is typically afforded in an A. The same situation does not ring true to me for men; new sex has ranged from "great" to "OMG" for me in my dating life (and little of that has anything to do with the other woman, as you correctly said, it's in my mind) and I can't imagine that adding in the danger/taboo of an A would do anything but enhance that feeling. Short version, I am very skeptical of men saying "A sex was mediocre" because between knowing how "new sex" is for me and hearing stories from men I know who've cheated, "mediocre" is literally never something I've heard in reference to A sex.
I'm sorry you have this issue, and I'm also sorry that I (and others) seem to frame this as an exclusively male problem, it's not (obviously), it's a problem for anyone who places a high value on their individual sexuality. And that group includes both sexes, some parts of it are harder for men, some parts are harder for women, but they all suck.