Well, you could turn down the ED and apply to other school next year. No one can force you to go to college now.
But do it because you want to go to Harvard or Yale or Princeton, not because you want to show your GC that he was wrong. You’ll be applying on your own because you’ll have graduated and your GC will have moved on.
My kids didn’t meet with their GC once, not once, about college selection. They applied on their own with nothing from the guidance office (we ordered transcripts and picked them up to mail in). You, your parents, and the GC had to sign the ED application. You didn’t have to apply anywhere ED if you didn’t want to go to Cornell.