It's a difficult time, but it's also an exciting time in your husband and family's life. You husband shows great courage in admitting to a problem. Alcoholism is progressive, and it's a good first step he is recognizing it, before it shows up as more of a problem for himself and his family.
I'm inclined to believe your children sensed tension, or that something was amiss, but did not have words nor an explanation for what it was.
You and your husband will have decide together the best course of action in what to tell your 12 year old. It's common for some treatment centers to have a family counseling component to the treatment. It's typically best to be open and honest. Explain the addiction as similar to a physical illness such as Diabetes, broken arm, etc. and with those illnesses it's important to get treatment in order to heal, to be healthy. Asking your son what his understanding of addiction/alcoholism is may be a good start. Many schools teach this as part of a health curriculum in school.
Letting your son know that he can ask any questions, and that you will answer them the best you can, or that you will gather information to help him to understand. Seeing his father be brave, honest, and authentic, is an excellent role model for him. This is a teachable moment of time in his life. The for sure thing in life is strife and struggle. His father is a good example of taking the road, that may be difficult, but will offer many rewards afterwards.
You are right that the stereotypical alcoholic is someone who is more down and out in life, have trouble maintaining a job, and or are abusive to the family. This is a good example, that this is not the case. It is amazing that so many people abuse alcohol and drugs for numerous years, and appear to "function". However, over time it can affect a person physically, and mentally- it is progressive.
As part of the treatment for alcoholism one needs to look at their thinking patterns- "stinkin thinkin" it is referred to in the alcohol and drug (AODA) treatment field. An excellent resource for you and your family is Alanon, a support group for those who love an alcoholic.
http://al-anon.alateen.org/home This is the website for Alanon
There is a tab for "teens" on the site, and "how can I help my children" can offer you assistance in explaining the disease to your son.
I'm sorry I missed you on line. Continue to ask questions or make comments until you get the information that is most helpful to you.
Thank you for your post on Just Answer.
Thank you for your response. My husband teaches at a school, how will I respond when the students/teachers/professionals ask where he is?