How Sad....
I am so sorry for your loss. You are so right in the three things you wrote. I truly believe there are some people that want to quit and just can't stay quit.
They are lost in their addiction until something tragic happens. This is what happened to my son. I believe the drug/alcohol combination is bringing our younger generation to their bottoms or death much sooner than just the alcoholic with the alcohol.
My thoughts and prayers are with you and your children....so many feelings must be circling your house.... :praying
kelsh