How to get over a crush?

There is a woman that I like so much at my uni.we're doing the same course and almost every week we'll meet in the class. sometimes we talked to each other and since last year, my feelings toward her grew stronger and stronger. she's always nice to me. she's cute and cheerful person. to make it short, last easter break, i tried to ask her out twice but both of them she said she's busy or had to go somewhere else. i was a lil bit disappointed and dejected. after that, we kinda not really talking to each other and she seems tryng to stay away from me. but, the problem is i couldn't stop thinking about her and just last night i had a dream about her (it's a non-dirty dream). so, please help me. it's so suffering to be in this kind of state. fyi, i have social anxiety disorder.