I am reading A Night To Remember and there doesn't seem to be any mention of the ship breaking into two pieces like the movie depicts. I remember something about this being a confirmed theory but the book doesn't give any hint that it happened.
It was a point of contention, but survivors such as Jack Thayer said it broke in two. He even drew sketches of it: http://www.titanicuniverse.com/wp-content/uploads/2014/07/titanic-survivor-stories-jack-thayer-drawing.jpg
Second Officer Lightoller, the highest ranking officer to survive, said it sank intact at both the American and British Inquiries, as did others.
The break definitely wouldn't have been as dramatic as the movie makes it appear. This Society of Naval Architects and Marine Engineers paper talks about the break. It may be a little dense, but check out pages 10 and 11 for pictures and the Passenger Testimony section. The break happened on the surface, but remember that it was dark, so it was felt and heard more than seen.
Not sure what you mean by "confirmed theory", but we know the Titanic broke into two pieces because it was found in two pieces by Robert Ballard in 1985 (A Night to Remember was published in 1955). Here you can see the bow and stern separated by about a half mile. Prior to his discovery, there was quite a bit of doubt about the eyewitness accounts that said it broke in two.
