Your child has already inherited the gene that predisposes him/her to addiction. 50% of all adults who were raised in the home where addiction was present either end up addicted or married to an addict. The rest of us suffer from depression, low self-esteem, eating disorders and so forth. Many have combos, me, I ended up marrying/living with them. My childhood living in the home of an A, was sheer h@ll, I lived it and I would not wish it on any child.
If he is smoking pot he is not in recovery. This is a progressive disease, very few pot smokers just stick to pot, especially if they started at a young age. I would imagine that
he has tried a thing or two else by now.
He has told you that he will continue to use, you either accept it, or leave. He is right, you knew that he was a user when you hooked up with him and you knew it when you had a child with him, now you want him to change? May be a little late.
My best..Dolly