>Losing her as a friend really fucking sucked because she was the only person I talked to for nearly all of 2007. That's why I began hanging out with my friends again.

I hope you learned a lesson from that, lad.

>The worse the breakup, the more your friend will hate you for dating her.

... and the more your friend will need his friends (that's you) to be supportive and around him. I really cannot see that happen if you start dating the girl.

Maybe some weeks or monthes later, when he's got over it, and most important after asking him what he thinks about it (well, if he's a close friend and you really don't want to lose him). He might be hurt by that, but this move will prove you that in the end you value your friendship more than the girl, and he will probably end up telling you he doesn't care. If he tells you that would horribly hurt and disappoint him... don't do it. Seriously. Unless you think this is the girl of your life and you want to marry her on the spot (and even then...)