I don't understand the exact situation that led up to the crash but this is my opinion.
First- Take pictures and plenty of them showing the scene. Have you gone to court yet for the ticket? If so, were you found guilty? If you haven't gone to court, GET A LAWYER AND FIGHT THE HELL OUT OF IT. Make sure you take pictures of the stop lights and such.
He can go after however much money as he wants but the judge is to decide how much he is actually awarded.
Did you basically cut him off and he hit you from behind? If thats the case, then definitely want to argue. How can you say if you had a red light then he had one? As well as, what does it mean he wasn't standing at the light?
If he sues you for more than your insurance company will cover, the court will basically stick you with payments that come out of your pocket.
If you feel his suit is unjust and you feel that he is at fault, you can always file a countersuit.
All in all, you MUST get a lawyer!