Mistress, I Was Wrong - Chapter 183 (1)

Bai Aoxue, the best mercenary in the 21st century, is accidentally sent back to the Chengxi Dynasty in Great Continent due to an explosion in her mission, and trapped in the first daughter of Prime Minister. After her rebirth, she is set up by her father to marry the 5th prince Jun Yeyan who wears a mask all day long.
In the face of bloodthirsty enemies, discord between brothers, collusion among courtiers and invasion of enemy state, can Bai and Jun resolve the crises? What will happen to their political marriage? How will the fierce battle for the throne end?
With many twists and turns, the book brings you to experience palace revolution, love and hatred thousands of years ago.

- Description from Novelupdates

Bai Ran had been married to Chen Chen for three years—three years in a secret marriage, only to have him hand her a divorce agreement. He asked her to sign it because he wanted to give his ultimate unattainable lover, Hu Wan, a beautiful ending. Chen Chen said, "Go and see Hu Wan tomorrow. If she asks you, tell her that you already have a boyfriend." Bai Ran said, "Okay." Chen Chen said, "You have to do everything it takes to convince her and make her happy." Bai Ran answered, "Okay." Staring at Bai Ranran's calm face, Chen Chen felt an inexplicable sense of frustration and uneasiness. Seeing the lack of hesitation on Bai Ran's face as she signed the divorce agreement, Chen Chen regretted it. To Bai Ran, ever since she signed the divorce agreement, Chen Chen's name had been erased from her memory. Even though she had loved him for more than ten years, once she gave up, she would never look back.

It has been more than ten years since he was transported to another world. The protagonist Deris Fahrenheit, who has became a magician with special circumstances, was freely enjoying his life in this world. However, a girl appeared before him and asked him to make her his disciple. That girl seems to be a transported person――

It’s a story of him who becomes the girl’s teacher and trains her to achieve her revenge (?) in otherworld.