What should I do in my situation?

alright so This guy I've known since I was in 6th grade Josh* (we are both in 11th now) is best friends with this other girl named Kristin*. Now they have known each other since 9th grade. Kristin* was a big problem with me and has called me names and doesn't want to be friends at all with me. I've told Josh* this and all he says is "oh lord" or "oh goodness". She has also caused problems by cussing at Josh* for "ignoring" her b/c he was hanging out w/ me..pulled his shirt ect. Now Josh* is still her best friend through all she has done with him and me. I don't know whether I should be mad at Josh* for still being her best friend b/c he won't stick up for me what so ever. This girl is physico and clingy. What should I do to resolve this???