I thought I was having a rough time lately, you've just put our few issues into perspective as I would be in meltdown over this, especially if I had witnessed what you had. To add insult etc. he's throwing a sickie with no doubt a claim to follow........
You have my sympathy, I can't imagine he won't be going the whole hog with a personal injury claim, a fair bit of time off work etc.
This entire claim may well end up against your policy, unless you counter claim against the third party. If so then this will have to be advised during every insurance quote you get. In a word I'd say you're buggered.
One point, and it'll be an important one. Never admit liability at the scene. It's not your place to do so, it's for the insurances to battle out later. I know you saw the prang and in uour opinion he was in the wrong, but the insurance co might decide differently based on the facts as they see them.
One final point, do you not have a company vehicle / driver policy?