On the topic of wanting him back, I so completely understand. And it might be a bit early for this, but as someone who took someone back, I wish I had known what it would be like, before I did it. I should've really, but I just missed him so much - and also a part of me did want to 'win' over the OW.
What I really wanted, of course, was not just for him to come back, but for everything to be back. For it not to have happened. I wanted to trust him. But I couldn't take away the fact that he'd done it, and I couldn't get over the thought that he could do it again. Sure, he tried to make it ok (ish), but I'm not sure he could ever have done enough. I'm don't think it's possible, honestly, to repair that. Maybe you can move on in a different way, but I certainly couldn't.
The months I spent back with him were the worst months of my life. A million times worse than not having him. It was torture, not knowing if he wanted to be elsewhere, not trusting him, not ever able to relax. The damage to my self-esteem was massive.
In the end, it was me that ended it. He had the gall to be 'heartbroken' and play the victim to all our friends. Because he 'really wanted it to work' and I was being some grudge-holding, jealous harpy. In a way, that time is what did the most damage to our ability to get along now.