For the nosy casual acquaintance:
"We certainly do not know each other well enough for me to disclose the details at this time.
(I actually used this it and it worked ,shut them right up!!!)
You can share with people as much or as little information that you choose. Personally I would keep it brief, and change the subject.
One of the best sayings I have ever read on this board, it has got me thru some sticky situations after the break-up. (some folks insist on being so judgemental)
IT'S NONE OF MY BUSINESS WHAT OTHERS ARE SAYING ABOUT ME......................