How old were you when you found out that Santa isn't real?

For many years, I believed that Santa was real, like most children do. I’d wait for new year’s eve all year, and that night I always tried to stay up and see Santa (note: where I live, Santa isn’t called Santa Claus, but anyway. And I think in other places the kids get their presents on Christmas) and that was what I was waiting for, the rest of the year.
When I was eight, one of my classmates told me that there was no Santa, and that the presents under the Christmas tree were bought by our parents. It made me so sad, and I hated that person for two years or so. I wish he hadn’t told me. Nothing was the same after that.

So, how old were you when you found out/somebody told you that Santa doesn’t exist? How did you react? How did you feel?

I was sad for many days after that