Man, that really does suck!!! Sorry to hear it!
BTW, and I know it probably has nothing to do with what happened, but 15 feet at 70 mph is not even close to a "safe distance". Do the math*. At 70 mph, you need to be over 200 feet behind the vehicle in front of you to be at the very closest "safe" distance.
*You should always be at least 2 seconds behind the vehicle in front of you, regardless of speed. At 70 mph, you are travelling at over 102 feet per second, so in order to be 2 seconds behind, you would have to be over 200 feet back.
Take care,
~Chris