Hi bidgdrunner,
It's an honest and heartbreaking letter. Like so, so many that I have seen written and shared here by people who are married to alcoholics. I think if it will make you feel as though you have done everything you could to help your wife and get her to understand how her actions are affecting you and the children, then go ahead and give it to her.
I have to be honest with you. I've never known a single one of those letters to have an affect on the alcoholic partner in the entire time I've been here. Although I hope, in this case, your wife is the exception. I also hope you will do what you can to protect your children and give them peaceful lives free from the drama and chaos of active alcoholism. It's a life that you deserve as well. But if and when that happens is in your control.