Yeah, she was fighting her inner demons and she became a nun now
Yup. (๑•ㅂ•)و✧There were two "Lucia" sharing a single body and what we've seen all this time between those two happened in their consciousness/mind. You can take it like two spirits, the original Lucia and the reincarnator share the same body just as you concluded.
I'm actually a bit confused about it but to my understanding when one day og lucia is fighting for her life with her sickness some stupid bitch entered her consciousness and took over her body. She could only control it when reincarnated bitch lucia is sleeping. Those panels where they're talking is just happening inside of their consciousness. Also when og lucia said she love "her" she doesn't mean the reincarnated but her self. Og lucia lock reincarnated bitch lucia to a room (again this is only happening to their consciousness) so that she can't control her body any longer.
I hope you understood my explanation
I may be dumb can someone explain what's going on with the 2 Lucia situation?? so there's two of her in her mind? OG Lucia and the transmigrated Lucia?