w/o/w: I hear. You don’t have to fall into the trap of believing he doesn’t care. He is your son, you are his mother, it’s likely he will always care. His outward presentation may not show this, but often outward appearances betray true feelings. He probably not only cares about not hurting you, but also cares that you approve of him. I know, hard to believe right now.
Just a thought on the walk you took to check things out. Sometimes even if you suspect or know what he is doing, the impact of seeing him do it is very powerful and can evoke very strong emotional reaction. On the one hand, you don’t want to be naive or in the dark totally about what he is doing, on the other hand, knowing all the details can be devastating. Since there was a confrontation of sorts, it might be worthwhile to try to talk it out, trying to convey your intentions in the most positive way, that you object to the smoking because you care about his lungs and health, that you want to make sure his internet use doesn’t do long term damage that will be difficult to undo, etc….