"Good, thanks for asking" or "I am well, and you?" or just "Good!"
and if he says "are you sure?" just respond with "yes"
if you respond with anything other than 'closed' answers, he may start to dig a little with questions like "what do you mean?". This allows him to find out where you sit with things without him revealing how he is feeling which is not fair. If you don't want him to know you're hurting, don't give him any openings to see that you are hurting.
At least...this is the advice that I should take!!
I would love for those reading this thread to check out my latest...I stuffed up last night. Now I am the baddie.