I Got Reincarnated As a Villain in a Novel

Male lead, why do you propose to the villain and not the heroine!? Having the strongest man in the empire as father, the most beautiful woman as mother and three arrogant brothers, there was beauty, power and irreducible wealth no matter how much you use it. I came to possess the villainess who had everything in the novel named 'Cielle Valentine' In the original story, the heroine was the adopted sister of Cielle. In the original story, Cielle had an unrequited love for the prince who chose her sister. Blinded by jealousy, Cielle bullied the heroine and so was executed in the hands of the male lead prince. So going back, Yes I reincarnated in the body of Cielle...But the problem is..Cielle is supposed to be a woman right? What the heck am I in the body of a boy!? Though I'm a boy in my past life, that does not make sense! "Young Master, Ceil." And her name is Ceil now!? And she is a he now! And that's me!? What the heck! In the original story, jealousy along with tormenting others caused her to get beheaded by the prince. But now I will avoid any of that! I will behave and maintain my good relationship with them. For now, I will try my best for my sister and the male lead to end up together...... "Young Master, Ciel, please marry me." Male lead, why are you proposing to me!? I'm not gay! Well..maybe I am!?