No, I don't think you are nuts. I'm not sure if it's a step forward or backward though. You've expressed very well some of the thoughts I have.
Right now, I think I know in my head it's over but I feel frozen too. And just like you I can feel so peaceful when he's gone or when I'm away and when I have to return or know he's returning I feel myself switch. I get anxious, feel trapped, dread what will be said and how he'll act and then how I'll feel.
And then we have some good times together, laugh, enjoy an activity together. And inevitably he does something that makes me 'feel' he's going out to send a text or make a phone call, and I feel the disappointment all over again and am mad at myself for being taken in by his 'niceness' to me. I get that lump in my throat too, and lots of memories of what has happened reappear in my mind.
I hadn't thought of it as a step in the process I have to go through to finally resolve my feelings for him and be able to end it all. I find that a comforting thought. If it is that, I can feel a little better about myself. I also just want him to leave on his own so I can avoid making that decision.
I also think that both you and I probably have other times when we have resolve and great fortitude about doing the difficult confrontations that need to happen. It's kind of like righting the ship...we may wobble back and forth during the process but the momentum is on our side.