beta
I think Huimin is actually crazy and really does have DID. That's why the ML wanted the original paintings gone and was concerned about MC remembering. The paintings were probably a trigger. The ML is def a regressor that probably got tagged in after the MC's heat. The reason I'm still going down the MC might actually have DID route is also cause he muscle memoried the painting he made and still manages to recall things he shouldn't. A lot of reincarnation manhwa/novels, when they have this plot point, tend to end on some kind of plot twist like that.
The MC lived in the OG time line at one point with the original ML then died. Then cause the ML keeps regressing the MC is also retaining the original "memories" as a book because his trauma will not let him believe he actually lived a life like that. The alt reality probably also happened but as a fantasy, or a fake reality, the alter MC used to cope and told a previous ML. He remembers these thing then is trying to help the MC live through his desires to keep him happy and mentally healthy.