Mate, you are in deep poo sorry to say. The 2.8 is an interference motor and you would be very lucky not to have bent the valves.
You may be able to fit a new belt and tensioner as well as a new idler, you won't know if anything is bent until you time it up and see if it will turn over (BY HAND ONLY)
Other than that the head needs to come off.
You will need to remove the harmonic balancer, when you put it back on, make sure to do it up to tension spec and loctite the big bolt.
Good idea to use a new bolt each time too.
Contact Nizzbits on here for genuine parts at a good price.
nizzbits@hotmail.com
So that's the weekend up the creek.
Cheers, the ferret.