Karen, Ugggg! BIG hugs from me... He didn't move out today, but may later this week! How arrogantly inconsiderate of your feelings. But then that's been how it's been for you. I wonder why he didn't do it today? It makes me wonder if he really is going to do at all. Maybe his plans are falling apart.
You mentioned that he is depressed? If he is depressed he is delusional if he thinks moving out and being with OW is going to make him happy. Happiness starts with each of us, we can't depend on someone else for that.
I know you haven't seen much of him lately. Perhaps you can keep up that trend... pretend that he is already gone. For all intents and purposes he already is.
But I'm so sorry you're going through this. It's so tough.