I wouldn't say there are three different turning points. The main climax of the book is the point in which Julia and Winston are in their "secret" apartment above Mr. Charrington's junk shop and they get caught by the Thought Police. Everything leads up to this seemingly harmless bit of Paradise and freedom that these two characters indulge in; however, it is quite against the law and policy of The Party (whose main purpose to gain power over its own people for the sake of having power).
From there, we go inside The Ministry of Love with Winston and learn more about the Party's policies from within its confines. The resolution of the book, then, is the only one it could be: vaporization of Winston.