How would you respond?

Hoping some of you may be able to come up with a response that I might feel better about using... Here's the situation:

My husband and I found out a couple months ago that we can't have children. When we tell people, I'd say 8 out of 10 immediately respond with, "So who is it??"

We find this to be rather insensitive and intrusive. If we wanted to explain the cause of our infertility, we would have done so on our own.

So far, our response to these people has been, "We're not discussing/sharing that."

What would your response be to these people? Once we tell them that we've decided to adopt, the insensitive and ignorant remarks keep coming, at a lesser frequency than the "who is it" question, but still. If they could just feel our heartbreak for a second, I'm sure they'd think before they'd say such stupid things...or at least I'd like to hope.

Sorry. Half vent, half requiring feedback 😂