The purpose of the al-anon meeting is for yourself to work on yourself. So the precise nature of your H's affliction is rather irrelevant. You can simply say that you are concerned that you are co-dependent, or that your brother is an alcoholic, or that your husband engages in extramarital activities and other behaviors compulsively. It doesn't much matter.
What you examine is yourself, not your partner.
What can it hurt to spend 6 hours on something free that might help?
