Your husband seems to be saying -- and more importantly, DOING -- all the right things. Had he said "Let me just call her, and get some 'closure' on this thing" or something like that, I would have been concerned. But he seems genuinely remorseful.
I think continuing to work with the MC should help you, and yes, it gets better (at least it did for me) and the images will eventually go mostly away. I still think of my wife with her OM every now and again, but that almost seems like a DIFFERENT Mrs. Puppy to me, so it doesn't affect me as much, if that makes any sense?
If the "fatal attraction" stuff persists, you may want to call the police. That should scare her off, before she starts boiling your bunnies.
