Every one keeps asking me this!!!!?

my best friends name is Madison and she is sooo funny! i love her so much (as a friend). but sometimes she's really rude to other people. like today after school she went up to my ex and knocked his hat off and accidentally hit him in the eye. all his stuff went flying so i went to go help him pick it up (i kinda like him too). his eye was watering like crazy too. when he left she was like geez he didn't need to cry about it. then my other friend saw all that and was texted me saying wtf? she's so rude. and i was like i know and she's like so then why are you friends with her? everyone asks me that!!! idk what to do? i want to still be friends with her i just wish she would cut out the rudness.