I don't think there is anything that you can do, IMO. To me, this is like asking how to make an in denial alcoholic realize that they actually are an alcoholic. Also, not all spouses of alcoholics are equal and not all parents are equal. I personally think my 2 year old picked up on a lot of what was/is happening where as other people think its way too young for a child to even comprehend more than "dad is acting weird, mom and dad are fighting, I'm scared."
For me personally, the best child related "advice" came from people who already had walked a mile in similar shoes. I feel like there are so many other wives & husbands married to addicts, with children, who can tell me about their own similar experiences and sometimes its their eerily similar experiences that halt me in my tracks and make me think. That did/does make me feel like they really understand and have experienced what I'm going through and already have come out the other side. And usually for the better.
I also feel its important to add, that while only one parent mat be an addict I think it's very common for both parents to have issues to overcome. I was reluctant to buy in at first but I'm a firm believer that both sides really do need recovery, especially if there are children involved.