Huge hugs omg, it's so hard
If he won't go to NA and or rehab just yet i would suggest you get involved with a nar-anon group or al- anon if there isn't a nar-anon near you. You will be able to connect with other family members of addicts.
I haven't been on your side of the fence but I've been the addict and I can relate to the absolute lack of self worth and love. You're right, nobody aspires to grow up to be an addict, there's always a reason.
I don't know what else to suggest, massive hugs xoxo