Toaru Majutsu no Index: Genesis Testament - Volume 5, Chapter 1: A Year Ending, a Wallet Emptying, a Struggle Ensuing – Winter_Vacation.

A teenager named Evan Mason was reincarnated into the magical world of Harry Potter and goes to school at Hogwarts!
With only his knowledge of the future and great talent for magic, he takes the path towards the top of the magic world, only to realize that ever step he took, changed everything!

- Description from Novelupdates

Lin Wanwan is a pitiful mentally-disabled girl. Not only does she suffer abuse from her stepmother, her stepmother even attempts to use her as a sexual commodity to pleasure others. Eventually, the poor Wanwan dies from an overdose…

Dual cultivation and apocalypse—words that mix like oil and water. There's nothing charming about seducing feral women on the road.

However, when Kaze Lexicon, the emperor of the Immortal Plane, got transmigrated into the past, he refused to give up his debaucherous ways—apocalypse or otherwise.

Armed with the knowledge of the future and an encyclopedia of overpowered cultivation techniques, he immediately set forth to obtain resources and build a lavish settlement to live a comfortable life dual cultivating in the apocalypse.

However, while it's obscenely protected and powerful, he finds himself in another predicament. The cultivators farming humans for their war, and the desperate humans, become enemies far more dangerous than the zombies and monsters that afflict humanity.

Join Kaze as he rebuilds his reputation from a bullied weeb, obtains wealth, builds power, starts a faction, makes lemonade, trains his people, protects his past lovers, conquers settlements, and fights humans, monsters, and cultivators, all for the sake of two obscene goals: enjoying life and building an army of engineers to bring modern technology to the higher planes.

Time travel to become a false widow, with a little bun beside her.

The parents-in-law were unkind, and the sister-in-law was tricky, so they jointly poisoned her to death.

Dong Yue was reborn. Faced with such a tragic situation, she was too lazy to entangle with these beasts and wanted to take Baozi away.

***

The general knelt down to intercede for the guilty minister: “He was framed.”

Everyone sighed: the general is kind.

Dong Yuezhi: He was the one who framed him.

The general ran to imprison the prince: “The prince will not do anything rebellious.”

Everyone sighed: The general is upright.

Dong Yuezhi: Running around is true, just to let the prince be convicted of the crime.

***

He is the only one who is sincere to her.

“Yueyue, I’m stupid, I can’t say good things, I will protect you for the rest of my life.”

“Stupid mouth?” With a simple and honest face, his mouth turned up and down, making people never turn over, “General, stop pretending!”

He restrained his simple and honest expression, and his eyes were deep and burning: “You are the person I love the most!”

[He has killed countless enemies and achieved countless battles, until he met her, and her every move touched his heart]

[She is versatile, there is nothing she can’t solve, but this man has become a candy that can’t be shaken off]

- Description from novelbuddy