It just breaks my heart

So J.'s SIL (let's call her K.) is a very nosey person. She is a stay at home mom and her connection to the adult world is attempting to be in everyone's business. For better or worse I gave in to her questions about why we weren't pregnant yet.
In the nicest way I can I have been slowly letting her know that her constant questions and implications is very hurtful to those who are unable to get pregnant by looking at their spouse like she is. I guess I need to be more blunt.
J.'s cousin has a 3 year old. We were unable to make it to that side of the family's Christmas earlier in December, but I of course heard all about it from K. She said that while the girls were playing with their presents she was telling the 3 year old that she should tell Mommy and Daddy to give her a brother or sister. . . wouldn't it be nice to have someone to play with. . . she doesn't want to be an only child. . . on and on. Well her mom started crying and told K. that they have been trying to "give her a sibling" but haven't been able to get pregnant.
It just broke my heart to hear this story. Seriously, has nothing I said to her made her the least bit more sensitive to conversations like that?!?!
I know she doesn't understand what we are going through. She even admitted that she takes for granted the fact that they got pregnant so easily, but I think it is all things that she says in order to get out of these embarrassing situations.
It just breaks my heart to hear about more people having to go through this pain that we have gone through. I wouldn't wish this on anyone!