What’s your opinion on weed?

Recently found my SO smoking weed and I told him I didn’t like it so he said he’d stop. Then I walked in on him smoking one day when I got off work really early and he tried to hide it and lie about it but eventually told me that he’d been smoking it because it helped him sleep and “take the edge off.” He’s a recovering alcoholic/addict so I guess part of my mind attributes weed to harder drugs especially when he said that he uses it as a way to take the edge off. I told him I didn’t want to be with him if he continued to smoke anything (cigarettes included). He said he’d stop because it’s not worth giving up our relationship. Am I overreacting? I come from a very conservative family and can’t put my finger on why I don’t agree with people smoking marijuana other than I don’t like seeing the man I love with his eyes glazed over and feeling like he’s not present or like his normal self. There’s so many views on why weed is or isn’t good so I’d like input from both sides.