If asked I might say something like "I didn't choose this road, and I am committed to marriage in all but a few extreme situations; unfortunately this road was given to me and I have been faced with one of those situations. I'd prefer to leave it there as my goal is to avoid unnecessary damage to the relationships and family that remain."
Me:38 XW:38 T:11 years M:8 years Kids: S14, D11, D7 BD/Move out day: 6/17/14, D final Dec 15