love solutions

i am in a one side love relation with her, she already has a boyfriend. we are classmates. we were in a friendship relationship for about a month and then i proposed her but smiled and walked away. but still after we were friends we used to meet in library for hours. . . .but after few days it was on my B'day i invited her but due to some circumstances she was unable to come. it was my blunder mistake i was drunk and broke our relationship. but now i realize da mistake i have done. i want to make upto her. don't know how to start??? please do help me. . . .