Detachment is about not being reactive. It is not about acting like your SO or his actions don't matter. Detachment should be part of a good M.
I think it was the perfect opportunity to address the topic directly in terms of what you want -- he brought it up. "SO, no, I'm still confused about what is going on. If you could be direct with me about what is going on with OW and us in your head, that would be helpful."
