My husband and I have been living apart for over a year but we are about to tell my son it's going to be permanent (our divorce will be final in less than two weeks.)
I've talked to several professionals and read all the articles I can find on the topic and the common theme is to not place blame on the divorce on either parent while making sure you let the child know it is absolutely, unequivocally, not their fault. If you can both be there and make sure it's as loving as possible all the better.
Regarding alcoholism, I do think it's important to address that at some point as the children have been impacted no matter how much sheltering we might try to do. I think it's important for them to know what alcoholism is and the three Cs (they didnt cause it, can't control it and can't cure it.) But I think those two topics are better kept separate and should be based on their age level, what they are able to process and probably depends a lot on the extent of abuse, etc.
Not looking forward to our talk at all. Sending lots of positive thoughts your way. Hope it goes as well as possible!