How do i tell her that i dont want to be her friend anymore?

How do i tell my best friend i don't want to be her best friend anymore...i mean, she can really be mean and bossy and moody...she also only thinks about herself...i have got two other best friends...and they dont want to be her best friend anymore...everyine considers us as best friends and i dont even like her as much as i used to...she was being really mean and rude to one of my best friends and she was insulting her...and thats what kinda made me not like her as much as i used to...i tried talking to my mom,but made it sound like i was the bad guy...me and my other two best friends like it better as us three...we have tried avoiding her at recess...but she always follows us...we have tried to talk to her at recess about it,we said we dont really like her as much as we used to,but she cried and it made me feel guilty...so i said we will give her another chance...and i really regret saying that...someone please...i dont want to be her friend anymore...but how do i tell her?