Forced to Marry Into Certain Death, Only to Farm the Battlefield Into Godhood?

Li Wei, a young man from 21st century Earth, found herself transmigrated into a parallel high-martial world as Wu University’s prospective freshman Li Wei.
Inheriting the original host’s memories and emotions, she decided to “marry” herself off to save her terminally ill younger brother, taking on the role of the Gu family’s eldest son’s “wife” to fight on the battlefield in his stead, waging war against the Abyss.
But no one knew that Li Wei possessed a system capable of absorbing energy from slain monsters to enhance her abilities!
What others saw as the hellish Western Frontier Death Line became Li Wei’s personal harvesting ground.
If you asked her, “Why not safely grind monsters within the Martial Alliance’s controlled Abyss rifts?”
She’d retort, “Why bother grinding myself when I can just sit in a bunker and let firearms do the work?”
And if you dared accuse her, “Isn’t this cheating?”
She’d fly into a rage: “Li Xiaowei does! Not! Cheat!”