Why should you pay?
Your dogs being let loose, were the result of a criminal act, the police would appear to agree with that.
You have suffered enough, both financially and emotionally.
There is no legal or moral obligation to pay this man for anything, he sounds like a right moron.
Next time he calls, tell him firmly, that he must take the matter up with his insurance company and that on the advice of your solicitor you cannot enter into any further discussion about this incident.