For brd - I know this is a tough situation for your friend's family and their friends. I would, however, like to interject one little thought for you. If he had indeed run out of the energy to confront the realities of his life - to the point that ALL other considerations were over-ridden - then he has found a peacefulness of heart that he was willing to pay the ultimate price for. No matter how confusing it is for those left behind, at least they can know that he is no longer suffering. And he was suffering, or else this wouldn't have been the choice - trust me on this.
I'm sorry for the pain that those left behind must find a way to deal with - and I know it is very hard. But I am thankful that he no longer lives with total despair.