Give him things from u guys and his cousins not big things but maybe a hair bow or a toy car stuff like that maybe a ear ring and give him a special box or bag for it that he can carry around all the time and make sure he understands y he's getting this stuff and knos that this takes place of the underwear and socks. My oldest sons birth mother is over in Afghanistan she left him a ring and he keeps that along with something of mine in a special bag so if I'm at work and he's lonely he will have those 2 show him we are still around and right with him. It works good luck!
You might be right. If so, you could try to address it by promising he will never be alone from you again, but if so you are going to have to live up to that. Drug addiction is very tough and it creates a precarious situation. If you are certain you and his dad will never use again, you can make this promise to your son, but you have to change a whole lot in a life to get the kind of regular schedule and calm approach to life that would reassure a toddler. In other words, in his heart he knows the situation is iffy, and the only thing that will cure that, is it no longer being iffy.