I am starting to realize that part of what led him here is the need to be seen as the great guy / charming / sexy, ... and in the case of the LTA partner, as a KISA. That desire was so powerful, that he was willing to blow everything in his life up for it.
So now ... to reconcile, he has to experience the reverse - as you say: the shame and the guilt. He doesn't get to be the saintly martyr or the KISA. He has to be the flawed guy making amends. And that is hard for anyone, but particularly for someone who was so overwhelmed by his own pain in recent years, that he was willing to throw his wife (me) under a bus.
Maybe as you say, he won't be able to focus on love, until he can get over his own ego issues.
He keeps talking about how he is going to do the right thing in the future. And how can I react negatively to that? Except that it bugs me. It feels like a shortcut. Like if he promises to do all the right things, then he can skip all the shame and guilt and go back to feeling like he is the martyr. But until he can focus on loving me .. I just don't have confidence that he can get beyond his selfish focus on his own needs - even if the foremost need is to see himself as the good guy.