I'm so sorry to hear of your hurt. I experienced this shocking situation as well..in September. It is so very hard to comprehend. BUT...starting Al Anon right away helped me keep my sanity. I also went into therapy myself to deal with the grief. Then I found SR...and there is what seems like a thousand years of wisdom in this forum. I've learned it's unrealistic to expect rational behavior or rational decisions from an alcoholic. I read "Under the Influence" and learned about the physical changes to their brains...preventing them from thinking or behaving in a rational manner. I learned that having a wonderful life, a beautiful home and a loving relationship could not compete with his addiction. The very moment I asked him to choose our life or drinking, he made his decision so quickly...that it took my breath away. Starting a recovery process myself was the only way I could survive this.
You have the additional hurt of small children. Dealing with your own broken heart and theirs too. It must feel unbearable to you.
I hope you can find your way to Al Anon, there is a loving supportive group somewhere near you. Perhaps you'll spend some time reading here, and perhaps you can get some help from real people. (family or friends near you>) The destruction of alcoholism is much more than many of us can bear alone.
Big hug to you.....my heart goes out to you and your children.