How is her drinking affecting you/your children? If her mother was an alcoholic, you have even more reason to be concerned.
One piece of advice on the sit-down/friendly discussion. I'm in the process of this now and I have one piece of advice: if your W proposes something that you're not 100% comfortable with and you don't have an immediate counter proposal, calmly say I don't know or I need to think about that. You do not want to commit to anything where you have any doubts, as this will affect you and your children for the rest of your lives. After the discussion, feel free to soul search and/or consult with your L to find the right counter proposal. And remember that an amicable agreement will likely mean that both of will have mixed emotions about the outcome; neither of you will get everything you want/your way.
Gordie 40s W 40s M20+ kids 2016 BD W fantasy affair w OM1 I do everything wrong 2017 I start to DB W says TLTL files for D PA w OM2 2018 I do LRT W drops filing and OM2 situation slowly improving