Why am I becoming so antisocial?

[J]

Don't hurt yourself! It's not worth it! You're just turning into an introvert. Introverts are the quiet people. You're not anti social, you're just in an awkward phase and finding yourself and realizing that you're not as social as you used to be.
Try to find an art class or instrument that you might like and put all your emotions into it. Introverted people like you are actually quite common, and if you find something like that you like you'll be really good at it and meet people just like you. Try writing. I'm awful in school and not very pretty, but once I pick up a pen at the end of the day and write out my emotions, I'm refreshed and feel better.

P.s. If your " friend"ever slaps you again, slap her back. As an introvert, people like her will try to take advantage of you and be mean. Don't let them. A friend wouldn't slap you. She's just being a jerk because she knows you won't do anything.

Stay strong! Find your true meaning and your center! Once you have that, no one can hurt you, and you'll love yourself.