I have had many bad friend situations. Now, i am 25 years old, and i grew up in LA. A lot of my bad friend situations were with friends that i knew in high school. They've stolen boyfrends, said bad things, etc... but the one that hurt the most, but also helped the most was the most recent one. This year, a friend of mine of 10 years( and not all of it was good) found a boyfriend. I didn't like him at all, but it was not my place to say it to her, because he was important to her. (he wasn't bad or dangerous, i just didn't like him.) She and i have had a temultuos relationship, but were very close. Her boyfriend thought i was too outspoken, and the things i experienced were false ( i'm a chef, so lots of drama and excitment happens during service, and to the average person, some of it may seem a bit out there). Now, she had only known this guy for 2-3 months, but took every word to heart. She didn't call for like 1.5 months, and then i got an e-mail out of the blue.  
She started off by calling me a liar- now there's my biggest pet peeve- liars- so i was immediatly defensive. and then proceeded to tell me EVERYTHING she didn't like about me- i'm a smoker(she is too) i won't go out with her (i don't do frat bars- and i have a career that requires a lot of my energy. The last thing i want to do is hang out with a bunch of spoiled rich kids who's worst problem is that their daddy didn't buy the right color of beemer.) anyway, she went on for 3 pages about how much i suck.  
3 years ago, i would have cried and apologised and asked her what i couls do to change. Now, not so much. I have found my authentic self, and along with that, my career, my new husband, and a very happy life i didn't even know was possible!My theory on certain bad friend situations, is if they can't like YOU, they probably never will, so why wast your time. I haven't spoken with her in almost a yaer, and i feel a bit lighter, and safer knowing the people around me are trustworthy of my heart.