Yep, he'll continue to tumble down to the bottom of the rabbit hole. I agree w/you....nobody knows where he'll stop. It's a shame he's ruined his relationship w/his son.
Mandy, your son is very wise for his age and he'll do well as an adult because he's had you for support and encouragement. Now, the question is...what is Mandy doing for herself these days?
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.