i'm sorry for your, and the other family's, pain and suffering. whenever someone is killed in any accident, automotive or otherwise, it's terrible for all the survivors.
one of my best friends is currently serving a 2-year sentence for vehicular manslaughter. it was a single-vehicle accident, neither of the occupants was belted in, there were no witnesses and he doesn't remember what happened. his passenger was ejected from the vehicle. both his family and the passenger's are in a lot of pain, and have been since it happened. they are all getting through it with help.
i'd suggest counseling - either from a professional counselor or a member of the clergy. perhaps both. and that's for everyone involved - not just your fm, but you and anyone else close to either side of the accident.
if it helps any, you and your fm will be in my prayers tonight.