You have read that book for a long time

(Grammar Questions I Couldn't Answer)

I was at the airport with my wife (at the end of our trip to Quang Ngai), and I pulled Don Quixote out of my bag to read for a while.
(By the way, it is taking me forever to work through this book.  Whisky was right.)

"You have read that book for a long time," my wife (L1 Vietnamese) remarked.

Being an English teacher, I couldn't resist correcting her.  "You have been reading that book for a long time,' I said.

"I think 'you have read' is correct," my wife said.  "We use the present perfect for an action that started in the past and continues to the present.  So I should say, 'you have read' ".

"But in this case, you want to put the emphasis on the fact that the activity is still continuing," I said.  "So it's 'you have been reading' . "

But my wife still disagreed.  "But you can say, 'You have lived there for two years,' so can't you also say, 'You have read that book for two years' ?"

Actually, truth be told, despite having taught present perfect continuous in the classroom many times now, I've never really felt comfortable with it.
I've always tried to follow the rules in the textbook when teaching it to students, but I've also always felt that the rules in the textbooks never really fully explained the difference between the present perfect continuous and the present simple.

And yet, in this case, my native speaker intuition was clearly telling me that "You have read that book for a long time" was incorrect, and it needed to be in the present perfect continuous.

After puzzling this out for a while (and re-reading parts of The English Verb), I've decided that the reason is because the simple tense of any verb sees the event as whole and indivisible.
Because the reading of the book is only half finished, the necessary forrm is "you have been reading".

...but let me through it out to the blogospher for a second opinion.