Because I suffered from endometriosis, I was started on Depo Provera shots, which is a form of birth control, and the knowledge that I wasn't pregnant every month became a Godsend to me. We have come to the realization, that for whatever reason, it was a blessing that we had one child, and our one child is a true miracle. And we have the happiest marriage out of anyone I know. My husband is my best friend, and looking back I am grateful for the life I had. I totally understand your feelings of people assuming that everyone is childless by choice. I remember having mere acquaintances asking my young son "When are your Mommy and Daddy gonna give you a brother or sister" and my heart breaking. It was so hard not to be rude to them. I finally got to the point of saying "I guess some things aren't in Gods plans". At that point I made a vow to never, ever ask a child free couple, "So when are you going to start your family".
People can say things that go right to the heart. I know. If it's any comfort. most don't mean to hurt you though.
Er, why the hell should you not be rude to them, given that they were extremely rude to you?
Civility, like peace, can only be preserved if aggression is met with a firm and devastating response.