how much will it cost to replace my bumper that has been crashed into?

I was on my way home from a family get together on christmas eve. there was a car speeding behind me. therer was a yellow light and i wasnt going to pass it on time so i was slowly stopping. the car behind me was still speeding at a 45 mile per hour zone and didnt stop. as the car was getting closer, the drive hit the breaks but didnt make it on time to stop, and hit my bumper causing it to get seriously damaged. how much will it cost to repair it ?