Well, it doesn't make sense to me, but I'll tell you my guess as to what's going on.
I imagine your H is struggling a little with his self-concept at the moment; he's trying to rectify some of the wrongs he's done, and some of that is so he can feel good about himself again. So, when it comes down to being a good guy, he probably feels a little stuck in the middle. Does a good guy use a woman and throw her away (firing her from her job, for example)? No he doens't. A good guy also doesn't keep his wife in a state of insecurity, so he might be a little touchy about it. If I'm right about this, it has to do with his feelings about himself and not the OW. So, what he told you might be the closest thing to the truth he's able to say.
He's probably in a constant state of anxiety about it (perhaps what you've detected on the phone) and would feel a lot better, some closure maybe, if she goes. The good news is that this can't last forever - it's just not a stable situation. Either she's going to leave on her own, or will do something inappropriate to the point where he'll have to ask her to leave. In the meantime, it's an elephant in the room that nobody wants to talk about (how did I get back to having elephants in the house? Full circle...)
Well, I could be totally off on this, but that's my speculation. Hope it's helpful!
