Hi Sue,
You're doing a great job of hanging in there despite the recent turn of events. However, don't get to wrapped up in him saying he wants to leave, even if he is looking at apartments. I get the impression that he is not in any hurry to move out. This is in your favor. Keep the course and continue to act "as-if" he may never move out.

For four months my W hunted for an apartment ... insisting she had to strike out on her own. Put some money down on a couple, but in the end never moved out and believe me I didn't get to the level of detachment that you have achieved until much later. My point is Sue, there is no certainty that he IS moving out yet, and Dbing is still more effective when there is more contact (even if it is just you showing him you can keep your distance when he needs it). So there is still (should I say a 50-50) chance it may never get to that point. Stay your ground ... you are still getting baby steps even if it is two steps forward ... one step back.