Sworn enemy noun phrase
Used to refer to a person whom you have a deep-seated hatred of
They used to be friends, but they have become sworn enemies.
They are our sworn enemy.
They were once sworn enemies, but now they are shaking hands and laughing happily together.
If you're off your trolley, your ideas or behaviour are crazy or insane.
You really think whether i'll pay the debt. You're off your trolley