what are friends for?

okay, this is.. not the 1st time i got fight with my closest friend in college. i know it was all my fault. because of credit semester. at the first,i entered a same class with her,but i suddeny i doubt with my choice about my class that i chose. because the class that i chose is start from 16.25 till 18 pm. oh no, i can't imagine that i get a night class,but lucky me,not overnight or the last class. i had no choice,i couldn't enter another class because it's full. so,me and my friend entered a same class in evening but i hope there's still a chance to get another class in the morning or afternoon. because i can't focus to study if i'm getting afternoon or night class.

okay, this afternoon,my other friend sent me bbm. it said that there's one chair to get afternoon class! let's get it fast! and then i got panic. i wasn't thinking of her or anyuthing. all i have to do is GET THAT CHAIR. one more chance! and ta-da! i got that class! praise the Lord!

 but..... after that i'm feeling guitly to my friend. she must be 'alone' on that class without me. yes i'm just her friend,i'm nothing to her and i was thought that she will be okay without me. but her bbm said that: okay i'm fine with it. you just go with ur own way.
ah no,i didn't mean that. i know i'm so selfish and egoist. i shouldn't take that chance before think that it must be someone that would be hurt if i went to that class. she must be think that i'm soooo ego,cruel. i will do anything for our friendship. i love her as a friend,as a sister. i don't want to take a fight with her. i asked for apologize to her. but.. i bet she must be hard to forgive me,because i'm the one to blame.

what should i do? i don't want to lose this friendship. what do you think guys? do you think that she would forgive me? i did a wrong thing.
yeah,me so sensitive person. when someone get mad at me,suddenly i got hurt and guilty.
what should i do?