I'm sorry your mom reacted in such a horrible way. You're not mentally twisted for having a dream, and while everyone will have a different opinion, for what it's worth, I do not think you're childish. In fact, I think that precisely what is wrong in this world is that at some ridiculous age like 10 or 11 we're forced to give up the wonderful world of imagination and creativity and all of a sudden learn to hate and analyze and ridicule every single part of ourselves and everyone else around us.
Hold onto your dreams. You may not be able to express them now, but you will someday. And it will be so much easier for you to do that if you have held onto them and carefully tended them then letting them get obliterated by miserable and insensitive people.
Good luck!