I think my fiancé is addicted :(

We got in a big fight the other day and I was angry and stormed off. Usually when I'm mad I just stay by myself for a little bit and come back when I've calmed down and he knows this. But this time he told me that when I left (it was only for 30 minutes) he had this huge urge to go out and buy an entire pack of cigarettes and smoke them all and he had to distract himself so he would not. And it's not just cigarettes, when something bad happens or when he gets stressed out the first think he thinks of if not cigarettes is beer, or weed. And don't get me wrong I'm not against weed or beer lol but the way he uses them I don't think it's healthy and frankly it worries me and it sounds like he's addicted sometimes, but then again maybe not because it's only when he's mad at me or stressed out? This isn't a big deal right? Tell me I'm over reacting about this? I mean people deal with stress in different ways right?