S.K.
I think you may want to casually distance yourself but if it were me, I wouldn't actually "break up" with her. My daughter (now in first grade) is in a similar situation. Her best friend from K (handful) is now in a different class - they play at recess and mom asks for playdates. Most times our schedules don't match up, and I'm glad about that. But I know kids change and over time, the friend may end up "settling down", so to speak. I don't want to burn any bridges. Even though she is a handful, she is an intelligent girl and when they do have the occasional playdate, I hear the conversations and I think she (the friend) actually is a good challenge to my daughter intellectually. I don't like how bossy she is (and try to give my daughter ways to speak up, as you also have done). But I try to think that there are some benefits of keeping the relationship "friendly" as I casually distance myself. Just my opinion. You never know - years down the road the girl may end up being the sweetest friend and you don't want to burn bridges. Just my two cents. good luck!