hey, ya'll gonna be playing in a campaign with some horror elements as we start at level 1 and homebrew and the dm gave us a choice on what body horror aspects we got to choose and rn im an order cleric 1

Crazy Faith
Your mind can't handle the horrid atmosphere of this place and you grab unto your faith as it was the last thing left, you hear voices of the "Angels" telling you to smite the opposing enemies. You have advantage on char saving throws, once you hit a creature with a melee attack/rangued attack, the creature takes an extra 1d8 of radiant damage. As a bonus action, you concentrate all of your power and make a powerful strike imbued in radiance, the creature takes a 2d12 spell attack ability.

You can only use this attack two times and to recharge all you must take a long rest

this is the aspect i chose

and i was wondering how to rp as a cleric that is pleasant and nice to be around but like a flip of the switch or a drop of the hat goes batshit unhinged crazy pants

p.s. they're not pretending to be nice or anything like that they actually are kind and compassionate but have a broken and unstable mental state and i also want to be respectful to people with mental illness if thats possible