Is it finished? This sounds like major psychological horror
i dont rememberrr because it had been so long since i read them or maybe it wasnt here, i might had read it somewhere else, other webs
Pretty sure it was this https://www.mangago.zone/read-manga/scandalous_wedding/
THANK YOU SO MUCH BABE LIFE SAVIOR
I read it long ago im not sure if it was a bl or not, but there was one scene where MC manipulate the already crazy and mental female character to believe that she actually a queen of different country with children, but in truth, she was just delusional and had mental illness, at first she deluded herself as the wife of the ML (no ML is single, even before he met MC). so, as tu 'get rid' of the crazy woman, MC brainwashed her into thinking she had been long married to a neighbouring king. They even lied to her (she has black hair) that the light made her hair blode thus explain the picture of the neighbouring king with his true blonde wife.