Please help me out.. I can't stop feeling heavily broken?

I am feeling very insecure over a guy. He used to show interest for about a year and I liked him too, but never showed it cos I'm shy, so the next year he stopped showing it and started to ignore me. (He's not shy.) Start of this year my timetable was being passed around and he kept his head down and wouldn't pass it on. I sent him a rose this year (school organized that you could send one to someone) but I guess I gave him mixed signals the next day. He tried to get a seat next to me in a very full room the next morning (but the girls wouldn't move along a seat) and I ignored him when he stared at me... but I'm just shy! Now he just ignores me. When we walk past each other he'll stare straight ahead or look away/down.. so I guess he's over it. I'm getting depressed over it and just feel like crying all the time. Advice?