In 1984 what happens in the book, from after Winston is caught until the end?

The second half of 1984 is all about
torture.  Winston is taken to the Ministry of Love, which is a machinery of torture: it
has torture chambers within torture chambers.

First,
Winston is broken physically.  He is beaten and starved.  Some of his teeth and hair
fall out.

Then, he is psychologically tortured by O'Brien,
who may very well be Big Brother himself.  O'Brien calmly begins the process of turning
Winston into a unperson.  He uses his mother and Julia against him: women are all
traitors; one must love Big Brother only.

To make sure his
psychological re-conditioning worked, O'Brien gets Winston to unthink even his most
basic thoughts by admitting that 2 + 2 = 5.

Then, O'Brien
uses Winston's worst fear against him: rats.  He puts Winston's head in a cage full of
rats until Winston confesses to being guilty of
thoughtcrime.

Finally, Winston is released to meet other
reformed thought criminals, including Julia.  We never know if she was a thought
criminal or a spy for Big Brother.  But, Winston treats her as he should, by calling her
"sister" instead of lover, which is the emotional equivalent of admitting that 2 + 2 =
5.