Little bit of a different idea: rework/revise the MS.
I'm someone who sometimes writes a bit long sometimes, too. I don't even think there's anything wrong with it--sometimes you need those words, they're there, readers just shouldn't see them in the final draft, if you know what I mean.
Any story can be revised. No book has just one *perfect* plot. The nature of plots and story arcs is that you can dig into them and shift them around. Tighter--and consequently shorter--is usually better than having the exact causality and set-up you need.
Again speaking as someone who's gone long before, you don't get to 573,000 words without some problems in the writing and story construction. It might seem perfect now but you can probably fix it. Have you had a beta reader? You can't post in SYW yet, but when you get your 50 posts here, put up a chapter or two. People will tell you if it's all set-up, if you're continuously overdescribing, or not controlling the pacing well. All of those things can be revised, but when they're there it's not hard to get to a whopping word count like that.
I'd really second mayqueen's advice to outline the story either in whatever format works. One good method I've used for dealing with structural issues is to write the three biggest story events on index cards and then stick them to my wall. Then I fit other events in around them, but only as many as I need. You'll start to see places you can skip the stuff that happens in-between plot points. The idea here isn't necessarily to split the book into four or five, though you may see some good spots to do that, too. It's too look at your own work analytically, and develop the self-awareness to recognize where it's working and where it isn't.
Yeah, writing is creative and pleasurable. Revising isn't. It's the work. It's also, IMO, where the actual magic happens--not some mythical Twilight Zone of the Pen in our subconscious. Revision is where writers show skill. It's where we can craft something for the reader. It's an important step towards publication, because publishing is writing for the reading public. Yes, it's our story. But we have to make it into something engaging to read.
Hope this helps.