This shows what can happen if your driving while your tired. I know at times I have almost fallen asleep driving with my family. When that happens I pull off the road and get out to wake up or take a nap.
I don't know if I can live with such guilt I might become suicidal. He is probably kicking his butt every day and how stupid it was to lose his family just because he fell asleep. I really feel sorry for him.
Probably its in the way you drive. I know that I can never fall asleep while driving because I drive a manual car. Also it is recommended that you take a different route where possible to get to home regularly, so that the trip home does not become monotonous.
Once a friend and I were driving in England and we both had a high temperature but had to be about some business. He tried to stay awake but at some point we BOTH were out and cross four lanes of a dual carriage way (highway) not knowing what happened. I won't go into miracles here.
JB, with all due respect, I think it was very irresponsible for both of you to drive under such conditions. You all could have killed someone. Not a smart choice at all.