I don't see any "wreck".
I see an impossibly tight chain.
Derailer pulleys can be replaced separately.
The Tourney derailer with integrated hanger as suggested by maddog will do fine.
But I don't see anything hopelessly wrong with the derailer you have.
What MIGHT happen - as it looks like you need a new chain - is that you'll have to replace the freewheel too, as sprockets and chains wear together.