Hi ~ Me again. He is living a lie, as we all see. Why oh why won't he just get it over with? The excuses he gives, 'they work at the same school', whatever, are lame if you ask me.

I guess I would be more forceful. Make him choose by cutting him off all together until he figures this out. The reason his wife wants him to cut contact with you is she already knows she doesn't want to share her husband with you. That is her fear. What do you think she would do if she knew the truth? Maybe that cat needs to be let out of the bag...
Let her be the one to dump him, maybe that would be easier for him, since he seems to think walking a tight rope between two women is all he can do.

He is one of the lucky ones; he already has the safety net (you) in place. This will be almost painless for him.
So What if his coworkers are scandalized. So What if it's hard. Aren't you worth the embarrassment and trouble this will cause?
I still think he needs to man up, stop making excuses, stop emailing you, and either be a husband, her husband, or yours. Not both. This is so unfair to everyone involved.

He needs to allow you or his wife the chance to move on. Is that his fear? That one of you will move on without him? Why is he being so selfish & self-absorbed?

Sorry to sound so harsh but this is seriously messing with people that he claims to care about. If he really cares, he will make up his mind and live with his decision. Doncha think?
Sincerely hoping for the best for all of you~