Responses

based on what i understand, my theory was right. what heumin considers as his 'fictional world' is apparently his 'real world' wherein all the cruel things being done to 'heumin' on the book was done to him by the ml, there's actually a lot of loopholes in my comment as i forgot the other details i'll try to paste my source below

https://www.mangago.zone/home/mangatopic/16637253/
you can read the rough spoiler here ^^
i'm too dumb to comprehend what's going on but my theory is also the same as with that one comment wherein heumin did not really transmigrated, but rather with the sudden death of their child, he isolated himself and his mind created another version of themselves in a different world to cope with his grief.
this is insaaanee i actually never thought it would turn like this like i expected this to be a not that unique abo story but daaaaamn okay it's making me feel on edge and excited for the next chapter