Sheesh, rj2. It kinda seems so obvious to me that I must be wrong! But I will say it anyway.
He is terrified! LOL. WE know he was miserable on his own...But he is having ALIEN memory lapse. He WANTS you to move back in AND he is doing a slight panic!!! It is understandable. He is probably entering the land of "what if...?" He's running all the tapes of uh-oh scenarios his little head can imagine. And he will do that for a while.
And, I believe you are doing it yourself, as well. Your fears may manifest in a slightly different way. (feeling your resentments, etc.) but you are probably also apprehensive.
Just remember your PMA and remember to DETACH a bit at the same time. AND keep your sense of mystery and freedom. Let him worry just a bit...so his focus isn't on the freedom (such as it was) but on who is this gal anyway? You know?
From outside perspective it seems quite natural for both of you to be jittery. It is a big step and, well, we are only used to searching for the baby steps...
Take it easy. Take it slow. give YOURSELF space to remember your strength...You will feel less resentful if you think about YOUR need for space rather than feeling pushed away by his need and his fear.
Anyway. That is my 2 cents. (Probably worth half that)