Start off with a BANG (literally)

probably neither

He's still hung up on his teacher's words and torturing himself thinking that his teacher was right and this is what he actually deserves.

I don't think so Nakyum saw that learned sir wasn't shit so doubt he still hung up on what that dickhead had to say.

I don't think so since even when the learned sir was going, he wanted to give him his drawing ╮(￣▽￣)╭ and nakyum never said anything about the learned sir, nakyum basically "agreed" with the learned sir and kinda called himself a whore

I'm pretty sure the only reason he resisted before was because he was so 'inlove'(idk what to call it) with the learned sir, that he didn't wanna do it with Seungho, cuz earlier chapter's said:
"Learned Sir: Nakyum doesn't do things I dont like" and I guess when the learned sir said to him that he was born a prostitute, his heart broke. So then he didn't have a reason to listen to his learned sir anymore or what he likes. Also earlier chapter's suggested that Nakyum did like it, he just refused to admit it, along with painting it, because of his learned sir.
This is just kind of a theory tho, and sorry if this doesn't make sense

I totally agree with you. Nakyum was trying to not like painting sex scenes or doing it with yoon coz of the learned sir.

Yeah, I agree with you.

Your theory is correct to be honest all of what you said is literally spelled out in the chapters. Suengho saw through all the bullshit. Nakyum was basically a drunk because he couldn't come to terms with drawing erotica because of the learned sir. Yes Suengho was and still seems somewhat toxic but the man has is as sharp as tack. He knew that even the learned sir was up to no good.

You reading the same story as me ? He didn't seem defeated to me more like clarity to hit him that he meant nothing to the learned sir.

I'm pretty I'm reading the same story it's just how I saw it ╮(￣▽￣)╭ to each his own

I'm not a dude