How hard is it to get into Berklee College of Music?

I'm a female guitarist, and I've been playing guitar for around 5 years. Music is something i've always wanted to pursue a career in. The main problem i'm having is music theory. I know that they require you to sight read in the audition. I have less than a year to learn SOMETHING, and i'm afraid i wouldn't get accepted because i know nothing about reading music. Im really talented at playing guitar though, and i can improvise well. I'm just feeling really discouraged now and if i didn't get into Berklee i'm not really sure what i'd do. I just want to know if anyone can give me advice on what to do. Would a year of practice help, or is learning music theory something that takes a really long time to develop?