I'm not going to say definitively whose "fault" it was, but the car behind you is not the biggest risk. The biggest risks are almost always in front of you-- cars pulling out of intersections, opening doors, and cars making sudden right-hand turns into your lane without seeing you. This has been my experience and the statistics bear this out (
http://bicyclesafe.com/).
If you're going to get hit from behind, it's probably because you swerved or a driver (going much faster than you) didn't see you and extra speed is not going to save you. Surviving the initial hit because you were riding fast doesn't mean much when your body slams into a guardrail or some other stationary object at 45 miles per hour.