My thoughts are with you. My brother was a heroin addict amongst other things and when my brother was in jail was the only time my mother could sleep at night because she knew he was eating and had a roof over his head.
Since my husband is an alcoholic I worry about my son falling to the same fate. He's only eight and I worry already.
I have learned to let go with love for my husband.
I'm sure your son would just like letters from you that you love him. You don't have to support him but him knowing he's cared for probably would help if he choses recovery. I am not familiar with your story so I'm sorry if I sound like I have no clue. hahaha
I can't imagine.