I am really, really sorry to see this. I absolutley HATE when this happens.
A related tale: I drove my husband'* new truck to work one day, and a supplier of ours here at work backed his van right into the pickup, hard enought to rock it, and then he drove off! Luckily 3 other people and myself saw it and called the suppliers office, and after dicking me around for a week, I threatened legal action unless they reported it to their insurance and got it taken care of. They caused over $700 worth of damage!!! People that do this are the biggest asshats in the world.
If I where you, I'd at least get the bumper repainted. Pay your deductible and use insurance. Thats why people have it. If you leave it, it will flake and get worse, and good luck getting a decent price if you are ever to sell it!
Dont leave your car with a black eye!