Not so great "best friend"?

My best friend isn't a good friend at all.. If somethings not her way she won't even go with it.. Its gotten so bad.. she is an absolute B to all my boyfriends.. She doesn't care if they make me happy she just screams at them for no reason.. For real SCREAMS ecspecially my bf im with now that makes me soooo happy..Recently she has been hanging out with this girl that moved from our town to another but has become a complete skank and now she's becoming one too.. Shes ditching me for the other girl all the time and always telling me about the new guys she made out with each party she goes to.. She's like even setting up rumors about herself being pregnant and constantely saying some new guy likes her.. Wth?.. She told me about a concert with ALL my favorite bands coming near our town soon saying "WE HAVE TO GO!!" Then decided randomly shes going to take a friend cuz she doesnt wanna see all the same bands as me and we'll hang IF we see each other there.. She dodged around the offer of meeting up there.. i REALLY don't want to be her friend anymore.. I mean is it just me or is this the complete opposite of how a friend should be?? I don't wanna just completely be like we're not friends anymore so any advice on how to make new friends so I can easily drop her?