How long is too long?

More than a year and a half has passed since I finished the first draft of The Difficult Novel.  Once again, I am working on it.  It's not half as bad as I thought.  In fact, it's quite good, which is reassuring.  But it remains difficult.  I'm concerned that it takes too long to get going.  If this was a story of Beauty and the Beast (to use an analogy), then you have to wait until chapter 14 to meet the Beast!  But the greatest difficulty lies in its length.  I wrote the novel with one chapter per document, thus had no way of telling how long the novel was.  Part of my current edit is getting all those chapters into one document.  I'm up to chapter 18 and already I'm over 90 000 words.  I suspect that this novel is close to 200 000 words.  Dear God, a serious door-stopper!  Who the hell would ever publish that!!  Who would even want to read it?!?  It's treacle slow and intensely detailed and I worry that no one would ever want to get to the phenomenal resolution.  It's worth it when you get there and I fear chopping the novel down (as virtually everyone might suggest) would take away the impact of the ending.
On the other hand, a novel of 800 000 words* recently won the Booker prize, so perhaps I shouldn't worry.  This Difficult Novel may be difficult for a reason:  two hundred thousand words of gold, perhaps.  Or so I keep telling myself.
Did anyone ever look at Michelangelo's David and say, hmm, no way, buddy, WAY too big.  It's not going to fit in any doorway.  You gotta cut the legs off. 
I don't want to cut the legs off my novel, ​she said obstinately.

* sorry, it wasn't 800K words but over 800 pages, which comes to only 267K words.  Perhaps there is no such thing as "too long".