this is my worst nightmare: something that I performed work on malfunctions and lives are lost. Mishaps occur. Sometimes, it is preventable. Sometimes, there is no amount of planning/engineering/contingencies that will allow for recovery. The amount of second-guessing and contemplation of "what could I have done?" can't be described in a number that I know of.
An earlier comment talked about remaining stoic at mission/launch control. It's the same for the knuckle-draggers on the ground as well. If anything, those directly involved with the launch have the hardest job. I personally don't think that I could have handled something like this the way that they did, so for that, I salute them and only hope that I can be half as awesome as they were on that day.