You: "I have no idea. How are you?" or " I don't know. How are you?" or "Not sure. How are you?"
Hopefully subject is change to the other person.
If they ask about your R with W:
"It ran it's course" or "We are not together anymore." Then ask about the other person. Make it about them and not you. Example "I like your coat, where did you get it?" can be used instead of How are you?"
"What is best for my kids is best for me" Amor Fati Link to quotes: https://www.divorcebusting.com/forums/ubbthreads.php?ubb=showflat&Number=2879712