Dart is totalled.. now what ?

You need to sue this guy AND his insurance company. You will NEVER get anywhere by talking to them, being nice, or asking.

If you have anything more than liability on the car, you need to get YOUR insurance company involved.

FIRST thing you need to do, if you have not, is GET THE CAR BACK from the tow company or insurance company and IN YOUR POSSESSION. This is YOUR car until the day you get a settlement.
X2. If you have the money, I would fix it and send them the bill. If they don't pay, sue the other guy for it. He'll contact his insurance company and put pressure on them from his side. You don't have to talk to his insurance company at all if you don't want to. He's the one that ran into you, not them. If you don't have the money to get it fixed, then a lawyer along with all your reciepts and info you can gather is the way to get that offer up to where it needs to be. If you can get it driveable, you can drive around and get some estimates for the repairs. Find several shops that do good work to get a concensus of what a quality job will cost. You don't need to accept an Earl Schieb job.