Why would anyone say that?

I don't rant too often, but here goes...
A lady at work introduced herself to me several weeks ago (we've both been there a while, our paths just never crossed much before).  At that time, she decided to play 50 questions with me (I didn't get a word in edgewise).  "Are you from here?  Are you married?  How long?"  And, of course, "do you have any kids?  No?  Is that by choice?"  (heart sink) 
Me: "Yeah, we just wanted to wait a little while." 
Then she proceeds to tell me that she is single (always has been) but that she adopted her son from another country when he was an infant.  I quickly got back to my business.  Well, today, we see each other again and she says, "I forget, are you married?"  Yep.  "Have any kids?"  Nope, just a dog.  "No kids by choice?"  To which I replied, "Um, yeah, it's by choice" and turned away.
Seriously?  First of all, we had already been through this.  Second of all...none of your %^&* business!  Why is it that some people just don't have social boundaries?  It is so heartwrenching to have to answer that question once let alone over and over- to the same person.  There were a lot of things running through my mind that I wanted  to say, but they would not have been appropriate.  I've been really upset about it because I am realizing more and more that it's the elephant in the room once people realize we've been married for 7 years and have no children.
We recently went to a wedding of one of my high school friends.  This was shortly after my m/c.  All of my friends that were there have 1+ children a piece, and none of them know of our infertility issues.  Interestingly, one of my friends cornered my husband and asks if we're still trying to have kids.  My husband thought it was odd but thought that maybe she at least knew we were trying.  Well she proceeds to go on about how hard that must be and how "that stings."  Yeah, I'm sure she knows since she got married and had a child less than a year later.  And, she always said she didn't want kids.  It just burns me up inside thinking about the conversation and how she was just probing for information.  I'm glad he didn't tell me till we got back to the hotel because I might have lost it.  
Ok, it's off my chest.  Time to move on.  I've got a lot to look forward to in the next few weeks and an FET in 35 days!