I read your post last night and this morning I'm still not quite sure what to say. It sounds like you had a good time last week, but the emotions took over in the end.
Quote: I read an e-mail she sent to a friend.
Shame on you! (but don't feel too bad about it, I can't seem to stop either!) But in that context, remember she is going to slam you to all her friends to validate her reasons for divorce.
And remember that we are supposed to believe none of what they say and only half of what they do.
Ok, so she slammed you to her friend. It's not the end of the world. And in a way she may be trying to hurt you by pushing your buttons; since she isn't ready to show her feelings for you.
As the others said, give her a little more space. She seems to keep coming back around and making a 400+ mile trip means something.
You know how well you treat her s. Keep focusing on yourself and building that relationship to include stepkids.
What I read in this is that you got a little too close for her comfort so she is pushing you away by hurting you to see if you have really changed or not. I may be overanalyzing, but there have been so many positive interactions.
Keep doing the things that work. And quit doing the things that don't!
Shame on you! (but don't feel too bad about it, I can't seem to stop either!) But in that context, remember she is going to slam you to all her friends to validate her reasons for divorce. 
