True Martial World - Chapter 1483: Somehow Predestined

In 1177 Jerusalem, Ethan Caldwell awakens as the leper king Baldwin IV, blending modern ingenuity with medieval valor. Introducing hwachas, windmills, and a revolutionary crossbow, he leads a crusade to conquer the Sinai, outwitting Saladin and transforming the Crusader states.

Unconditional obedience to him? Dream on! Regrettably, after marrying Tang Yuchen, An Ruo's daily thoughts were of escape, escape, and more escape! Someone grew furious, “You want to flee? The only way out is if you die, or I perish!” Fine, she chose death! Yet he laughed wickedly, “Woman, do you intend to kill the son in your womb?”

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!

- Description from Novelupdates

I became the childhood friend of the protagonist in a novel. The childhood friend who died from taking drugs.