Could it just be that you are having a moment? I mean this is very serious - divorce. I think its human nature to question and doubt. Maybe today isn't a good day, maybe you are tired - something that is making you think it wasn't that bad or it will be better than it was.
I can't answer what it would be like to go back. Cut yourself a break. See how you feel in a couple days. You might wake up tomorrow and say no way - or you may continue to think about it. Don't make a rash decision, and before you move back if that's what you decide you should spend as much time with him as possible. Sometimes all we need is a refresher course.