I think your "friend" should no longer be classified as such and they may need an education in traffic law. While no expert I am fairly confident that whoever was driving the car at the time of the incident is responsible and should also have adequate insurance to drive the car.
I would be confident in saying that is the same almost the world over. Why would you be responsible for crashing the car when you were not even in it. Call the cops. If your friend refuse to pay it then try escalating it to criminal damage with the cops.
Was your friend insured to drive your vehicle?
If so then he has to supply you with his details to sort this out, I am also confident that is the same or similar the world over. If not then you can tell the cops he was driving without insurance.
You do realise that your friend was working on orders from your ex boyfriend to get you to lend your car. The ex and his new gf's plan was to trash it from the start, you got played. Chalk it up to experience after this mess is done.