I'm going to tell my new boyfriend that I hate his music taste
Why do you want to tell your boyfriend that?
His music just annoys me.
You don't have to like everything your boyfriend likes but you shouldn't be mean about it and insult it. It will hurt your boyfriends feelings.
I don't really care. I can't be with someone whose taste would hurt my ears.
I think that you're overreacting just a bit. There's no need to insult his music choice, just let him listen to whatever he wants.