Hello caligirl;
Sadly, I never had children of my own, but I do know from speaking to other parents that sometimes, little kids lie....pretty big enormous ones....and these children have grown up in quite stable homes with no divorce, no alcoholism or addiction.
Perhaps a nice long talk about the truth and what it means to you would be a good start. Therapy is always an option you can explore as well.
Ultimately, growing up without active addiction is always the best thing for any child. Many hugs and prayers for your whole family as you move through all of this! HG