Your = possessive 2nd person pronoun: your cruelty. You're = contracted phrase "you are": you're a tasteless person. Failing to learn this in grade school does not reflect badly on your teachers. It means that you're a thick brick, so I have doubts about your taste in music.
so basically your friendship was contingent on being supportive, and now that this "friend" is moving to a new town, you can let it off your chest that you think having dreams is silly. You know what's actually silly, not having dreams and pursuing them. Even more silly, outing yourself anonymously to communicate to a community of anonymous people who are not your friend that you think having dreams is silly, and further, music is silly. What a waste, I have an old algebra text book if you need to flex your mind.