Antlers, hang in there man, I feel for you. I can relate to your situation somewhat as my STBXW is doing things I never thought she would. She's even threatened me about full custody of our DD and then saying "...but I think you're a good dad" WTF? I know I'm a great dad and was a good H too you narcisstic bi-polar crazy woman!
I agree with Gypsy that if you have the option of ending it sooner the better it'll be for your own well being. You sound like a good man. No one's perfect but what matters is that we own up and work on improving/fixing ourselves, it proves that we care enough to want to change.
Me: 35|WAW: 38|D: 6yo | http://tinyurl.com/2dxx7m6 Feb 2006, left, came back in two weeks Aug 2006, left again Apr 2007, filed for divorce Dec 2007, reunited Mar 2010, moved out, filed again