Why the heroine became the villainess?

How this happened? All I remembered that I was lying on the verge of death. I was stabbed by a crazy man. Now, the romance novel that I purchased that night, its villainess, Beatrice Delavine Croix, became who I am today. What should I do? I haven't completely read the novel. I only know that what awaits to the villainess Beatrice was a cruel death. I only knew the gist of the story, ONLY the summary and the marketing ads of the book.

Through the pen and paper given by Marielle, Roanne started to write what was she only knew about the story.

The villainess, Beatrice Delavine Croix, daughter of Marquess Croix, is the top candidate to be engaged to the Duke Aland's heir, Zeke Audric Aland. She and Zeke were a childhood friend that later on, she fell in love with him. Knowingly a spoiled woman, Beatrice tried everything at her hands to get the affection of Zeke which the latter finds annoyingly. She followed everywhere the young heir and when she found him, she clings to him like a leech.

The heroine of the novel, Canaria de Brishen, illegitimate daughter of Count Brishen, caught the attention of the young heir, Zeke, that caused the wrath and hatred of villainess Beatrice towards to heroine Canaria.
Villainess Beatrice bullied and planned wicked schemes to heroine Canaria. As a result of her evil doings to the heroine, it leads the ruins of the Marquess family and her cruel death.

As Roanne tried to crack the brain of the body that she already obtained, flashes of memories came to her. The memories of real Beatrice Delavine Croix started to come in.

*HOPE YOU ENJOY THE STORY. THIS IS THE FIRST TIME THAT I WRITE A DECENT STORY HERE. I AM NOT AN ENGLISH PROFICIENT SO PLEASE DONT MIND SO MUCH IF THERE IS GRAMMATICALLY ERROR THAT I HAVE MISSED.
MY FIRST WORK , WITH REGRET, I NEED TO DROP AS IT IS MADE OF MY YOUNG SELF. ^_^

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Photo credita to the novel, i dont want to get married.