Quick backstory.
Parked our car legally outside of our house. No lines or anything like that. Been parked there for years never any problem. We don’t have a driveway.
Neighbour at the other end of the street drives along our street blind drunk, swerves, hits our car almost writing it off, continues on his merry way, sort of parks up outside his house and gets home.
I witness this and confront him. He denies hitting our car despite me seeing him do it. Then he says we have obviously parked badly. He is very drunk, stinks of alcohol and police are called. Arrest him and he’s over the limit etc. We get his insurance details and our car is fixed to a tune of £6000. I don’t think much more of it and presume insurance are dealing with it.
6 MONTHS later I receive a letter to state he has denied hitting our car and we are now liable for the costs of the damage plus the hire car we were forced to have because he had smashed up ours while drink driving.
He is now denying the whole incident and apparently the police report is unrelated as they didn’t see him drive the car 
How can this possibly be fair 
We have spoken to our insurance company but apparently there is no proof despite the arrest and the photos of our car and his which was also damaged. He is denying it ever happening.
We stand to loose all of our no claims bonus also. We can’t really afford to have anything else go up and are struggling as it is 
Would I be unreasonable to knock on his door and call him a shitty drunken arsehole for this 