If he is paying for it, then go to an accident repair centre or two and get a quote, something similar on my Sons Citigo was about £550. We paid directly to avoid insurance claim on a non-driving fault for a 19yr old (he hit it whilst mucking about on his longboard in the drive).
If you go to your insurance and tell the whole story they will approach him for payment, either direct or via his house insurance, either way he will end up footing the bill.
In life, it's not who you know that's important, it's how your wife found out.