(take what i say with a grain of salt since i used a really shitty translator to read and i only read like 2 chapters with little context)
I skipped a bit ahead and i'd just like to say that even if heejae says/does cruel things to garam in the future, please understand that it's a defense mechanism.... i'm not excusing his actions entirely but he's obviously a hurt and lonely man who's scared of deeper connections.
I'm lowkey just scared his character might be misinterpreted ><;;;
it's so beautiful to see heejae realizing that he can't take garam's hate. he's treated every student with the same cruel and strict teachings, but heejae cannot resist the person and sound that garam is. he's now seeing how the hate he initial wanted is coming back to bite him since he's being blocked out from garam's world, and in turn the true depth of his sound that he carves.