Two friends of mine, both close, one was a roommate, were killed the day after Christmas 2004 on their snowmobiles. Drunk, riding stupid, at night on a lake they weren't familliar with, and hit a cable that cordoned off an open area of water despite the fact that it was marked with reflectors.
Broke one guy's neck and decapitated the other.
As wrenching as it was to lose two of your good friends at once, I knew that they had it coming with their reckless ways. Play with fire long enough and you are bound to get burned...
I am sorry to hear about the loss of your friend. I can relate, it is no fun to be the friend left behind.