Level 1 to Infinity: My Bloodline Is the Ultimate Cheat! - Chapter 4: The First Step to Dominance

Bathed in the love of her imperial family and her husband, Yun Shang was a spoiled princess and the envy of many at the Royal Court. Her life had been perfect right up till the moment when she realized that everything was just a sham, a ruse designed by the Empress to ruin Yun Shang. After enduring bitter treachery and being poisoned, Yun Shang died with a broken heart and an unfulfilled vow of vengeance. As if God was answering her final request, Yun Shang found herself reborn like an immortal phoenix. She was eight again, and all her memories from her previous life remained intact. The others, however, did not remember the events leading up to her death. Determined not to repeat her mistakes, Yun Shang planned to rain hellfire onto the treacherous, backstabbing villains for all the heart-wrenching pain they had once inflicted upon her. He was the handsome and smart prince of the Ning, who was revered as a battle-hardened general that knew no match in the world. He had thought he wouldn’t settle for anyone until she showed up. A seemingly innocent young princess and a gorgeous prince. Where would their relationship lead them?

- Description from Novelupdates

She was forced by her husband and his mistress to jump into the sea and commit suicide, only to be rescued and taken care of by the jerk's uncle for seven years.

It tells a poignant love story. He was the most heroic man in history, and before his death he sang a sad song about a woman; she was the most charming woman in history, and before her death she danced a story about steadfast love. The story of the two had no beginning, only an ending of parting in death. After his death, he became a demon for her, and fought fiercely with the immortals of the three realms. After he was killed, his unique seven souls were hidden in various places by the immortals; she became a ghost for him, and before she passed away, she smashed Meng Po's soup bowl, and her soul flew away. Even so, he still vowed to subvert the three realms, find her in the next reincarnation, and marry her, even if it took a thousand years.

I Became Hades, the God of the Underworld from Greek and Roman Mythology