What can I do for this girl to forgive me?

Me and one of my friends(girl) were having a fight on how bad I made her feel because I called her a ******** lazy hobo. I was just so angry when I saw her FB status that said something about having so much fun talking to her ex. As if I wasn't broken enough.. Anyways, I tried to say I'm sorry to her so many times last night but she just wouldn't, no matter how much I tried. She simply just wants to never talk to me again or be my friend again... I was mad but I still want to know what's the best thing I can do to try and gain her trust that I wouldn't say anything mean like that ever again.. Any ideas? Or should I just beat the crap out of her in my dreams?