Rebirth of the Heaven-Defying Demon Witch

On her wedding day, she was betrayed by her fiancé and close friends, and her entire family was wiped out. So, she swore a blood curse and sacrificed her soul. A hundred years later. She was reborn as a concubine. When she was tortured to death, her soul awakened and started a long road of revenge and transformation. ---- Call her a waste? She carries the spiritual teachings from her previous life with her. That she went through the back door? She found the strongest backer in the entire continent to back her up. That she is a witch? Well, she's going to be shady all the way to the end!