On a positive note, mdu, instead of asking him about him and OW, you turned it into a positive by asking about the two of you and treating OW as a nothing (which she is). Congrats on thinking that through before asking the question.
Me: 31, W: 29 T: 4 M: 2 Kids: 3 (SS: 7, SD: 4, D: 3) Separated, still living together: Nov 2013 Separate bedrooms: Feb 2014 W working away; kids with me: Nov 2014