I'm just going to tell you what my ex did. It worked and eventually I moved out.
Be firm, stand your ground, and do what you know is right to keep your sanity intact and give you peace of mind. We tried one therapy session, it was obvious it was never going to work out. Like you said, the damage has been done. Looking back, even though I wanted our marriage to work I know now that it wouldn't have lasted. The wounds were too deep. We used a mediator to split our assets evenly and to keep the divorce as friendly as possible. Yep, he'll probably get angry or depressed, and eventually he'll get over it too. Time heals, two years later my ex and I are not exactly the best of friends but our communication is slowly getting better.
As for your daughter, trust me when I tell you that children are incredibly resilient. Keep reinforcing that you both love her, avoid blaming your AH and remind him to do the same. In the beginning we told our kids "Mom and Dad love each other, but we can't live with each other anymore". Constant support and reinforcement of love are musts in my opinion. Having a family split up isnt an ideal situation, but I also noticed that our children were very much in tune to the unhappiness in the household. In the end a divorce was the best thing for all of us. My kids and I now have a relationship that's like a dream for this alcoholic, and I can see they have that with my ex too.
This article might be useful to you
http://www.ces.ncsu.edu/depts/fcs/hu...tsdivorce.html