SAhDaddy, thanks for your reply, your suggestions on dealing with the other relationship, and your thoughts on the issue of the OW calling my house. My fear is that, if I draw the line here, then he might prohibit me from calling him if there is a situation where he is with her and I need to contact him. He is already thinking in terms of putting this affair on an equal footing with our marriage, for example suggesting that maybe Saturday could be her day and Sunday my day. Now that she is moving into an apartment, my fear is that she will demand 50% equal time. But it isn't really equal because there are jobs that we do in our household, not just fun time. So I may need to make that point with him.
I have another question besides that one: If the OW were to break off the relationship, are there any support systems that would help him deal with the loss of that relationship? It really is like stopping an addiction -- there have to be some support systems to help deal with the process. I might as well be thinking about this now, in case we (hopefully) get to that point. Let me know if anyone has suggestions.