Your wife is still not "out of the fog" yet IMO.
As a firm rule, people who have dignity, self-respect, healthy boundaries and self-love do not have affairs, not only because of what it would do to others, but also because they would never lower themselves to do such a disgusting and destructive thing in the first place. Likewise, people with those same qualities also do not get (knowingly) involved with married people.
As a WS begins to "do the work" of going to IC/MC and digging deeper into their "whys", they should, over time, start to change from having a "cheater mindset" (no dignity or self-love/respect and unhealthy or missing boundaries) to that of a healthy and authentic person, someone who can own their bad choices and decisions, and who can empathize with others.
It is not at all unusual for a WS to "miss" the AP early on, in much the same way that an abused person may still love their abuser after leaving them. Over time however, the "brainwashing" starts to fade, and as reality sets in, the abused person starts to see the abuser for who they really were, and see themselves for who they really are as well. And in most cases, once the victim realizes that loved a person who never actually loved or respected them back, the "love" fades quickly and reality sets in. When the truth sets in, they begin to despise the abuser, and may despise themselves for not being stronger, etc.
This is what should happen to the WS. If they have truly done the work and learned to rebuild their dignity and self-worth, then they should be looking back at the AP for who they were. Disgusting people who were incapable of love just as much as your WS was/is. Someone they used to get what they needed at the time, and who used them back in the very same way. Someone you would never marry, let-alone date, in a million years.
If your wife still pines for the AP, then IMO, she's still broken. She still can't love herself enough to not miss the attention she got from them. And if she is not capable of loving or respecting herself enough to see the AP for who they are, then she certainly cannot love or respect you, not really, not in a healthy or meaningful way.
I don't say any of this to hurt you or discourage you from remaining in R. It took me YEARS to get my head out of my ass. Rather, it is my hope that you might be able to see your wife through the lens of "being a broken person" as opposed to the lens of "she loves someone else". She doesn't love anyone, she is not capable, at the moment. That doesn't mean that she DOES NOT love you to whatever degree she is capable of however, and I think that's important to keep in mind.
Think of it this way. I cannot lift 100lbs over my head. I'm too weak. But if I worked out every day, in time, I'd be able to lift it easily. In that same way, your wife cannot love others right now, she lacks the "strength" (self-love). But that can be remedied. If she does the work, then her ability to love you, herself and others, can return. It just takes a TON of hard work, bravery and dedication (and a willingness to fail A LOT and yet keep trying). But it can be done.