I was put off music as a subject at school too, the teacher was a really nasty, bitter and miserable sadistic type, shouldn't have been involved with kids under any circumstances.
I made a deliberate point of making a horrible racket when forced to sing, as we all were, in front of the class.. The unlucky, (or unwise) ones who gave a decent-ish performance were conscripted with no refusal option into the "choir" run by this creep.
Left me, I'm afraid to say, with a loathing of any sort of formal music education