I did the whole Santa Clause bit with my two daughters. Part of it was reliving my own childhood and wanting them to have the same fond memories I did. I don't recall a heart break moment for myself when I realized it was all a ruse. My parents never formally told me. It came on as a sneaking suspicion that eventually became obvious as I grew more aware of how the world really works. And I don't ever recall being pissed off at my folks for leading me on like that. There were still presents under the tree, so what did it really matter?
I'll ask my younger daughter in a few years how she sees it. It's especially interesting in her case, because she cracked the code on Santa, the Tooth Fairy and the Easter Bunny all at the same moment, when she recognized that the notes she'd been receiving from them were all in the same handwriting, and that didn't add up for her.