All the worry about whether we would finish or not has evaporated. Now I worry about looking at those old chapters we wrote back in the spring. Those chapters have been gathering dust for 5 or 6 months. Early drafts rarely age well. And I anticipate terror-filled dreams in which the editor hates it, really hates it, dreams in which the manuscript gets lost somehow and we have to rewrite the whole thing in a single day. Stuff like that.
Writers are nuts. Just nuts. But for this moment, I'm happy. We will finish this thing and turn it in on time. Whatever changes the editor wants, we'll make them. No problem.
Also, a finished draft means time to start thinking: What next?