I think it's interesting that so many of us define an entire friendship by its ending.
Nah, I just wish I had the guts to end it sooner. With the college friend I told off, I realized she wasn't a good friend during my second year of college, not during the end of my senior year which is when our "friendship" ended. At first, she came off as very friendly and generous...however, the more I got to know her, the more I realized she was calculating, selfish, and liked to take advantage of "emotional bullying" (something that girls like to use). Of course, I didn't care at the time because at the time I was an "ally" and she would just gossip to me about other people...and admittedly, I was too weak to say otherwise.
During the rest of my undergrad years, her attitude just got worse and worse (she was spreading vicious lies and half-truths about my other friends, made her weak-willed friends do incredulous "favors" for her, and would always make herself have a greater advantage over other people), and with my emotional state senior year, I just didn't want to deal with her...and I got on her "bad" side. I'm pretty sure she never thought I'd step up and tell her I didn't want to speak to her again because when I wrote her an e-mail calling her out, I never heard from her, ever.
The only thing I regret about cutting things off with her was falling out of touch with my other college friends, whom I'm sure she influenced one way or the other. Although she's definitely NOT the worse person I've ever met (there are other people I've met
far worse than she), I really would rather not associate with her ever again.