Q&A When Is It Appropriate to Tell Adult Children about Their Mother's Affair?

I've endured my wife's multiple affairs and alcohol addiction for the last dozen years. I am a few weeks away from finalizing divorce. I have tried to protect my wife's image to my children and haven't told them about the infidelity. They know that my wife has had a problem with alcohol and I took that route as a reason for divorce. My 19 year old daughter recently mentioned to me that she can only find fornication as a reason for divorce in scripture. I skirted the issue and gave her a non-answer. I don't want my kids to think I am just throwing away their mother and that I am a bad man. When is it appropriate to tell adult children about their mother's affair? How much do I disclose? Do I give their mother the opportunity to tell or do I?