Is she a true best friend or not?

me and my friend have been together for more thn 2 years we were soooo close tht we would talk about anythng she was a part of me and i was a part of her. one day her boy friend said something mean to her i went up to her bf and blasted in his face i was sooooooo damn mean to him for her even though her bf is a friend of mine. at that time i had a bf we were friends and all but it just didnt work out so he broke up wth me " whch i have no regrets over" but the next thing i knw it my bst friend is with him and i do believe she took advantage of the period of time whn we didnt talk during the break up to get closer to him and i didnt knw tht later on another friend came up to me and told me tht they were dating " i was the last person to knw" puttin in mind tht this guy really really hurt me so she told me tht she loved him and all .. i hate her for it and in a way i dont want to b around her but at the same time she is my friend and i have to support her. and what hurts more thn the break up is tht my bst friend did this to me and i sacrificed alot for her i mean i could havve dated the guy she was with but due to respect im not even gonna put tht in mind .. i feel she betrayed me and decieved me and whn i ended our friendship the frst time she blamed me so we wnt bak to our friendship and til now she still blames me as if im doing something wrong.. and the guy was like i was right for him at tht time but she was right for him at this time.... is she a friend or shd i just end this i mean i cant take it anymore i hate it whn she acts as if nthng happnd and whn i try to confront her she says he never loved u in the frst place im really really strting to hate all this i cant keep on pretending everythng is fine and her pretending tht she didnt do anythng wrong :S