Girlfriend Not Talking To Me, My Fault?

We're both 17 and had gotten into an silly argument at my house about a week ago, I started yelling at her and calling her names. She's a very conserved person and she just said leave me alone. I told her she can't run from his problems and to face them but she started to walk away. I tried grabbing her a couple of times and she kept saying don't touch me. I got really mad at her and slapped her by accident (It was a very light touch, not really a slap). She looked really upset and went home. I've tried talking to her over the last week, I've been texting her and calling everyday but she doesn't answer. Every time I see her at school she just walks away and doesn't let me get close to her. I'm really sorry for what I did and I promise I would never do it again. I just want my girlfriend back. How do I get her to talk to me again?