I have kids ranging in age from 27 to 11. I have twice had to face the news that my child would not live through the day and by the grace of GOD did not have to live through either ending in the loss of a child, once even signed organ donor papers to donate my oldest daughters organs. I just remember relying on the Lord for strength and comfort and praising him for the outcome. I still can't imagine your pain.
I have always said that parenting is the toughest job in the world and you have no idea how you're doing until it's probably to late to change it and often what you do or don't do doesn't seem to matter.
I have a 15yo that I'm sure is headed down a terrible road and he has no interest in changing directions and the rest of my children are either already productive members of society or seem to be headed that way, I don't know how it is that you love, teach and train them all the same and one goes so far off track but they will follow the road they chose sometimes and not the road you wish to lead them down.
I will pray for Gods comfort for you and your family.