I am taking a different approach here....given the unknown of your financial situation.
You have 5 children. He is currently living in his car. What's your end goal, here?
Can you consider letting your attorney help him get a job so that he can contribute to the court- ordered financial support of and health care insurance for his children?
In the long run, that's more important than having drug abuse/addiction appear on the divorce papers, that no one will see?
As for the rest......there is nothing about him that causes you to doubt yourself. The doubt is within you and about you. Please consider picking up a copy of Codependent No More by Melody Beattie. It's at your local library and used at Amazon for about $2. This simple book has changed many people's lives.