I dont know what to do, I'm falling for her but she has a boyfriend, should I tell her this?

Well, you two seem like an awesome pair of people and you should just say, 'You're my type, your boyfriend is lucky to have you. If I had a girl like you, I'd be the happiest guy on earth,' but say it in a joking tone, don't try to get her to break up with her boyfriend, just let her know you're availiable, and stay in her department, keep her happy.