I didn't stop believing until I was 23!!

The moment I first really new for sure, without a doubt that there was no Santa was my first Christmas as a homeowner. I was on my own and had to put all the gifts out while my DS and DH were asleep. When I woke up the next morning and all the presents were just as I had placed them and there was nothing under the tree that I had not put there it hit me- Santa really was not real. I always knew that he was not real in my mind but not until that morning did I know with my heart.
When I ask if my DS15 is glad I "lied" to him about Santa he says yes! I feel the same way!
If your DD still believes I say let her! If she is just pretending to still believe let her do that too. What's the rush? Would you really compromise that feeling your DD still has about magic so your sister will be happy?