Addressing another concern: revenge. Again, total honesty: I think in some part I was hoping it would make him jealous, but it didn't, and I genuinely like Mike, and my husband is genuinely okay with it.
The whole story about the secrecy with Mike to begin with is that he wasn't sure my husband really was okay with it, and his girlfriends didn't think it was a good idea, given where my husband and I were in our relationship. He knew they would be disappointed in him if he went ahead anyway. So, yeah, there's dishonesty there, still.
Not sure where we're going, now. Maybe it'll end tomorrow. Or not. Wish I had a crystal ball!