So sorry to hear your struggles, but good to hear that things are progressing in R with you and your WH.
Comparing yourself to the AP is a common thing we do as BSs. I think it has to do with trying to find some reason why our spouse would stray, risk destroying their family unit, and violate their spouse. Naturally, you'd like to believe that the AP must have had something, in order to risk so much.
Sadly, though, the AP usually is pretty deficient in many areas. In my case, my WW's AP was somewhat younger than me (5'ish years), which wasn't really a factor, but socioeconomically, he was at the bottom of the barrel. Not only did he "make a living" gambling in budget casinos, but he likely also sold drugs to supplement his gambling income. Last I heard, he lives on the couch of one of his friend's parents. In fact, the last time my WW and he went on a "date", he had to borrow $20 from a 17-year old kid to cover the lunch bill. So, naturally, my mind searches for how this guy could have been worth all the risk that my WW was taking. Literally, she was betting EVERYTHING on him.
And that's when I finally came to the realization that it isn't about the AP (appearance, integrity (of which they have none, BTW), honesty, character, stability, security, etc.). What it's really about is the WS! The WS is trying to fill an empty void within themselves, and will likely take whatever comes along. Usually, they have such low self-esteem and self-image, that they will unknowingly seek out some of society's most unsavory people, as that is what they feel they 'deserve'. For a BS, it's a very strange concept, and likely not one that we'll ever understand (nor likely ever experience). But you can take solace in knowing that it is highly likely that your WH's AP was 'picked' from the bottom of the barrel, and can in no way compete nor compare with you. Once this really sinks in, and you truly acknowledge it, you'll likely shift from comparing yourself to the AP, to simply feeling sorry for your WH.
Not sure if that helps or not.
Just my $0.02.
Best of luck to you.