if your friend started being mean would you still be their friend ?

I've actually had this happen to me :/ My best friend had started hanging around the bitches in school and started talking shit behind my back so I asked her about it, and the look on her face was answer enough, so I looked at her like she was stupid and told her, "Well go ahead and hang out with all your new fake friends, but don't come crying back to me when they stop talking to you because they realize all the annoying shit you do." Then i walked away with my head held high. It hurt, but she obviously didn't deserve my friendship if thats what she's gonna do.