What I did:
1. Pleaaded over the phone for her not to go
2. Shaved my entire body
3. Contemplated suicide
4. (after my roommate slapped some sense into me and hid my knives) asked her if I could see her one last time before I left her life
5. We went on a sad "farewell date" and I got the "we can still be friends" talk, went home and threw away everything I had that reminded me of her but fished them out of the dumpster the next day.
6. I resolved to win her back.
Long story short, through fluctuations between her hating my guts and yelling at me to her wanting me back but wanting to be sure I learned my lesson first, two things happened.
First of all, I straightened up my life and stopped being a pathetic slacker. Second, I finally convinced her months later that I wasn't just faking it to get her back.
We got back on friendly terms, but she'd get mad every time I mentioned getting back together. On the weekend before Valentine's Day, I came over to play Halo with her(yes she plays) and she broke down crying and asked me to come back. Why? Why not just move on? Because I'm the only person in the world other than her own mother that respects her. She missed the stability of having the one best friend she'd ever had, and now that I wasn't failing school and wasting my money on trinkets to ease my feeling of self-worthlessness(recovering emo, collecting things helped keep my mind off of it), she felt I was the only person left she had to rely on.
To cap that story, we're engaged and pretty happy now. Sadly, she had to move to the other side of the state, but I go see her a weekend out of every month. If I wasn't broke bc of the economy, we'd be married.