Fiance won’t stop smoking weed inside the bathroom while watching our baby

My fiance goes in the bathroom and turns on the ventilator and smokes weed and tobacco out a bong he made. Idc that he smokes, it’s the fact that it’s inside and he goes to get the baby right after. No hand washing or anything. He refuses to outside with it. Even worse it’s right next to her nursery and I would hope the smell wouldn’t get on her clothes. He smokes every hour and will try to get me to come smoke with him too and tries to make us leave our baby in another room by herself while he smokes. It’s an addiction at this point which makes me nervous because his mother was on pretty heavy drugs and I don’t want him to be that way. I’m thinking of moving out with just her and I because I worry for her health. We don’t even own a humidifier.