I told my 12 year old sister I don't love her
Why would you say something so mean to her?
Because she is a pest and never leaves me alone.
It is very hurtful to tell family members that you don't love them. She is bound to be very sad.
It's okay, I was only joking.
Joking or not, I think that it is hurtful to tell her that you do not love her. I think that you should go and apologize to her.