He's lying, he knew you were eavesdropping and is playing you for a fool.
Go to his house around dinner time and pound on the door. When he answers, (or if someone else answers, demand you see him) and say "Listen up you elitist fuck. You think you're so fucking cool that you have a girlfriend and you've been mocking me this whole time because of it. And don't think I didn't figure out your little ploy. You knew I was eavesdropping and so you tried to play me for a fool. But you're a terrible liar and I know what you're up to. If I didn't know better I'd think you were trying to make me jealous, f*gg*t.
Then kiss him hard on the lips, push him down, and take the carefully placed spaghetti from your pockets (with sauce) by the fistful and throw it at his family.
That'll do it.
