My older brother told me Santa wasn't real when I was only 5. When I started to cry, he laughed and told me the Easter Bunny and Tooth Fairy weren't real... they were just our mom and dad, too. I ran downstairs and yelled at my mom, "You lied to me!" and sobbed into my pillow, heartbroken. I can still remember how sick to my stomach and upset I felt. Ah, the loss of innocence. Then, we two were sworn to secrecy for the sake of our younger brother, who went on to believe until he was 11.
My ex had a son from a previous marriage; the Christmas that the little guy had just turned 3 years old, his mother was angry that we had him for Christmas Eve (we alternated years, per their divorce decree), so she told little man an hour before we arrived to retrieve him that there was no Santa Claus. We had a two hour car drive to listen to him cry and then when we arrived, I got to hold a heartbroken, clingy 3 year old until it was time to go to bed. All of us were miserable that year. I explained how Santa's spirit lives in each one of us and we create Christmas magic, but I think he was too young to grasp it all. I thought he was finally asleep when he crept down the stairs in his little footed pajamas and sobbed, "maybe we should put out cookies anyway... just in case." We put out a plate of cookies for Santa and a carrot for the reindeer. We elaborately left crumbs and a dirty milk glass on the table and on the snow, there were little chewed up pieces of carrot and "hoofprints" in the front yard when he awoke. He looked at me with huge shining solemn eyes and said, "maybe mom was wrong!"