My wife and I weren't able to conceive a baby. My wife however, is better spirited in terms of seeing and befriending other people with kids. At our nieces' dance recital over two years ago my sister-in-law mentioned that her single mere 21 year old niece on her in-law's side is there with her eight month old son. My wife went to see the baby and befriend the young mom who is young enough to be our daughter. I remained seated out of jealousy, having failed to pro-create on my part.

A couple days later, while my wife was out, I decided to post the single mom on FaceBook because she and my wife are "friends". I explained my reason for being unsociable at the dance. I did not make any hostile remarkes to her. I only mentioned my own sense of failure and loss. The worst I might have said was a silly which may have been taken as sarcastic form of congratulating her as in "con-a-er-ehh-gratulations I guess". Not particularly nice I admit, but not deserving of was to follow soon after.
As soon as my wife walked in she alerted me that her sister called her on her cel-phone and is furious because her daughters(our nieces), as they happened to be using FB at the time, saw my post and informed her about it. I was annoyed, considering I had no ill intent, and did not violate any online rules to the best of my knowledge. So my call her sister on the home phone to discuss it further and I, wanting to settle it fast and not have to have it on my mind picked up the phone and asked what the problem was. Her sister started shouting saying what I terrible thing I posted to her niece. I guess my biggest mistake, which to avoid making, is easier said than done while being shouted at, was that I shouted back instead of taking control and asking calmly why it was so terrible. But I started to shout loudly that "meanwhile all these hostile activist groups have their freedom of speech and nobody bothers them. After I started to explain that, she cursed at me and hung up.
In the past, the few feuds we've had were soon forgotton about. Our second oldest niece was to graduate High School later that month in June 2012.
I thought it over and decided it best not to attend while the incident was too recent. But things did not seem to "patch-up". The next year (June 2013) the third of our four nieces was to graduate, and the invitation was only addressed to my wife. The day of the graduation I wrote a letter to my sister-in-law stating that I had no intention of causing any upset and was not harrassing her niece with the baby and that I was only sharing my story, and mentioning that I did lose control but that she also did not have to curse at me, and now my wife and I can't be together on tonight because she is still carrying a grudge after a whole year went by.
After a few days my letter was received my sister-in-law's only comment to my wife about was that "she doesn't know what I'm talking about". Since then I did see my sister-in-law at an Aunt's funeral in October 2013. I said hello to her and she casually returned my greeting. But we did not exchange any more words.
My point is that I am concerned why this would infuriate anybody so much.