Is she really my true friend?

My best friend (or a person I though was my best friend) and I made plans about a month after the 4th of july last year (2010) we met each other on the 4th of july that year and thought it would be amazing to celebrate the fact were so close and it was because of our boyfriends we had at the time. We both got asked out with in the same two weeks. I got asked out on the 23ed on june and she got asked out on the 4th of july. we had our ups and downs with our boyfriends but me and her never ever had one fight. I was always there for her but she was never there for me. I always put her before my boyfriend but she didnt do so for me. I thought it was some teen age girl faze that i just didnt understand yet because she is two years older then me. She is 17 in 15. So I let her go through her faze. But then this kid cheated on her, talked **** and all this horrible stuff. I was there for her 100% of the way! Remind you I ditched my boyfriend for that whole month sue to her tears and sadness... And then they got back togeather. I knew it was going to happen. yet continued to let her live her life as she wants reminding her of how im always going to be ther for her. And again. A few months later dumped her. Now I know what it feels like to not fit in the world. My dad abused my, My step dad cheated on my mom and was a totall druggy and my mom is stressed and depressed. I know I loved my boyfriend. More then anything, But I knew to put my "Best friend" First cause Im aways there for her, She will one day return the favor. I have a hard time saying no. And I was in a situation where a guy wanted me to cheat on my boyfriend. And I couldnt, Just couldnt say no. And He took advantage of me. I told my boyfiend the next day and he left me. Not saying one word to me hr got up and left me. I tried to call, text and see him. And hes avoiding me. all i was thinking that day was "She is going to call and aske what happened" And later that night i got a call. SHE IS BITCHINgg AT ME! She hasent even heard my side of the story. She called my a slut. a skank and all this other stuff. Never thought I would be hearing this from her. But I told her the story and she under stood. One thing I love about her. Shes not a back stabbing *****. Or so i though... The fourth of july is coming up " Hey so are we still hanginfon the 4th of july?" I texted her today... she responded with no she has plans with her boyfriend she has made two weeks ago.... I tried to tell her we have had this planned out for about a year now... And she tol dme her boyfriend is more important then our friend ship.. then started telling me how its not her fault im a dirty whore who lost her boyfriend cause she cheated on him.. and im a gross slut and all this hurtfull stuff. Now I love my ex. More then enything and anyone. And it hit me. hurt so much. I snapped. I called her up bitching! I was shaking so hard all i could thing about was her face getting fuckedup by my fist. And she had teh guts to say she didnt want to talk to a slut like me.. Then had teh guts to say sorry and get mad at me for notaccepting it. And tried to tel me that shes my best friend -__- what do I do?