I'm the Final Boss Villainess He Must Kill

Hongyeon Kim has spent her afterlife generally being bored. So when a new program is introduced to entertain the dead, Hongyeon jumps at the chance to be transported into her favorite novel. However, when she finds herself in the body of the villainess, the demon princess Bella, she attempts a spell to speed up time to the end of the novel. Instead, she finds herself ten years in the past. Now, she must wait fifteen years to escape all while living with demons and raising the main character! (Source: Tapas)