/lit/ - Literature

I've been wanting to to write a novel/long story about one of my characters from this worldbuilding project i have been working on for a while, but i realized im in the worldbuilding trap and would like to pull myself out of that, with that aside the story takes place in a apocalyptic setting where people get realitybending powers and interdimensional mixups occur at earth due to an incident at CERN, the main character is unable to deal with the ensuing chaos and with her getting psychic abilities and a slow but sure involvement with a posthuman cult she's bound for a downwards spiral, my main question is if i should write in first person as if its some kind of mental/literal journey for her which gives opportunity to directly show her mental decay and unreliable narration or to just have it be third person where more character's thoughts are written aswell?