The real question is if the first car felt one or two bumps. Two bumps means you hit him first, then were pushed into him a second time when you stopped too quickly for the guy behind you OR one bump probably means you were pushed into him by the car behind you hitting you (unless you hit him first and left enough space that the guy who hit you did not push you into him [doubtful]). I WOULD NOT reveal this logic until you read the police report to see if car #1 says 1 or 2 bumps.
FWIU, you will always be at fault for hitting a car in front of you, but if the insurance determines that you were pushed into the car ahead of you AND you left enough space, then you are ok.
How many bumps did you feel? One, two, three or four?