I Am Sorry, but the Ending Is Already Messed Up

The female lead of the game dies, and her fiancé falls into despair. There is an epidemic that has no cure in the country.
A world after the ending that is referred to as ‘the most terrible, the worst, and the most disgusting’ in the game. I stood in the middle of that world, becoming the female lead’s twin sister and the villainess that killed her sister.
Oh, I’m screwed.
The new life ended before it even started.
My name is Fay Le O’Belle, the twin sister of the female lead, the blood of a beautiful fairy, and the last head of a prestigious family. It’s all useless. For me, ‘Fay’ is just a villainess that killed the female lead.
The ending is already messed up. There is no turning back. So I will live with my mouth shut like a dead rat.
“s*upid, arrogant, crazy….., did you kill René just for this?”
It’s apparently impossible. There’s a guy who already knows all the truth and is eager to kill me. He is René’s half-brother, Denev, who loves her.
From now on, I have to think about how to run away from him.
……in a world where everyone loves René, how can I, who killed René, save my life?
‘I don’t want to die even though I’m a villainess with a bad ending.’
All right. So, let’s run away first.