Sand Mage of the Burnt Desert - Chapter 229

In her previous life, Su Wenyue was driven by vanity. She abandoned her husband and child, ultimately meeting a tragic end when she was falsely accused and killed by the mistress of the house.

Her three-month-old unborn child perished with her. Meanwhile, the humble man she had looked down upon seized the opportunity in the chaotic times. He steadily climbed the ranks to become a high-ranking and powerful prime minister in the great kingdom.

Su Wenyue died in remorse. But upon awakening, she found herself back at the moment when she had just married into the Han family.

Since childhood Gu Wuji has regularly encountered ghosts and was one day involved in an infinite world of terror, just– I treated you as an evil spirit, why do you want to hug my thigh?

- Description from Novelupdates

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!