I'm going to tell a friend/dj why I really didn't want to go to his shows
Can you tell me the reason?
I think his music sucks and his band is mediocre
You should be kind to your friend and not rude if you don't like his music. You could offer advice to him on how to improve or try to do a collaboration.
I only said it because of the jealousy I had for him. I'm an asshole because I didn't want to give him credit for anything he has accomplished.
Well that seems really rude. If you actually like his music maybe you could ask to help him create a song or something.