Would I be childish?

Would I be childish if divorced my husband because he will not stop smoking weed? We’re both 25 and weed is not legal in our state. I knew he smoked when I got together with him when we were 17 but I didn’t think that 8 years later he would still be smoking. I’ve asked him plenty of times to stop but he always says he will and just ends up doing it behind my back and I end up catching him or finding out.. not sure what else to do..