>>28703411
Its only "working" because its temporarily riding on the remnants of the idler wheel.
The wheel is grinding into the belt, the belt is riding on the bearing that the wheel used to be mounted on.
You need to buy a new tensioner/idler (whichever it is) and a new belt.
>>28703393 (OP)
im more concerned about the rust lol i drive my cars through sand and dirt and mud and floods every day for years and it doesnt look that bad