That wasn't your sister/friend in that casket. That was a husk. Keep that smile in your mind and she will ALWAYS be in your heart. And because she's there you'll save on phone bills. You can talk to her anytime day or night. So talk to her. Tell her how you feel. If it feels better, go somewhere alone and talk out loud. It may sound off the wall, but don't worry about how or when you'll grieve. When you're ready, it'll happen in your own way. Right now your emotions are probably as turbulent as they've ever been but it'll be cool in time. I wouldn't lie.