I think you should tell him "Considering this is where OW lives, and you've lied to me multiple times before about your relationshp with her, I have no other choice than to believe that you're wanting to go there to be with her. Considering how tenuous our marriage is right now, do you really think this is the best decision?"
All you can do, Rileybug, is make this YOUR boundary. "I cannot feel safe in a marriage where my husband is transferring to a distant city -- the same city as a woman with whom he's been having an affair, and lied to me about it. If that's what you choose to do, then I guess we both have some serious decisions to make, because I won't live like that." (or something similar)
Riley, HE is the one who has lied to you and cheated on you. It's up to HIM to make YOU feel comfortable in your marriage again, not the other way around. What has he shown he is willing to do to EARN BACK your trust?
