Seeking Immortality, but in the End He Became a Demon Lord

It's a story about cultivating immortals, no routines, genius, decisive killing, passionate female protagonist, no male protagonist, (there is a plot of a woman disguised as a man) and it's a bit dark. Practice Qi to build the foundation, Yuanying transform into a god, overcome tribulations and ascend, become an immortal and become an ancestor, the road to immortality is long. Ten thousand years are just a snap of the fingers. Looking back, the past is like a passing cloud of smoke. After the Jedi Heavenly Power, immortals no longer exist in the world, and they rise as mortals in the mortal world. The first genius in martial arts ascends to the path of immortality, seeking the path of immortality, just to gain immortality.