No, your priority is your son, and you need to care for yourself to be the parent filling both roles.
Your ex has always chosen addiction over his partner and child. You are wise to keep your distance as he is literally just taken half a step in a lifetime journey of recovery.
If I were you I would focus on your son and your own future and let your ex work his program. He has experts, resources, and blood family to help him.
What resources do you have or can build towards your own recovery from living for years with a selfish and unreliable addict?
I would absolutely stay No Contact with him and his family for now.