I quite like it actually

I think it's not great Jooha has to go through that.
But I also think there's a reason. He has a nightmare bringing back memories of his rapist while actively getting raped.
It just shows how Dooshik always had that violence in him (since the twins) and that he sadly follows into Pilwon's footsteps. While it is awful, it's also very well written.

I just hope the author either keep Dooshik bad and Jooha runs away, or Dooshik is bad but Jooha stays and the whole cycle starts again or Dooshik realizes he's done bad things and just truly reflects.
Actually what I don't want is a happy ending because it would make no sense here. Because you don't get to rape people and be happy.