If you really like him, you need to pull him aside, set the record straight and apologize. Don't overdo the apology, but you did hurt his feelings.
Confess that you were caught by surprise with the question and you just froze. Tell him the truth is you do have a crush on him and that you don't know how he feels about you, especially since you may have hurt his feelings, but he's a great guy and you do have a crush on him. Add whatever you like about him or whatever makes him special.
Why you need to apologize IN PERSON is that your exclamation of "No way!" conveyed both rejection and disgust. Think about it. You were saying, "Ewww. No! Are you kidding?" You need to set this right for reasons of his self-esteem, even if he now doesn't like you back. Don't rely on texting or go-betweens. Show that you have integrity. Do it in person, girl!