Horrible to hear HIA, I feel for you. A colleague of mine did the same thing very recently, left behind a family. They weren't a friend, so I don't feel the loss personally like you, but it shakes you to the core.
As was said, try to help the family as much as you can, now and down the road. It's a terrible thing they have to live with. There's usually something deep, underlying in these instances when there isn't mental illness involved. I hope if it's something bad he was around or involved in, that the family doesn't necessarily have to find out, unless it would help their grieving process. They have enough to deal with the rest of their lives.
Stay strong, for them and yourself.