The account at Matthew 16:21-23 (BEB) reads:
"From that time Jesus went on to make clear to his disciples how he would have to go up to Jerusalem, and undergo much at the hands of those in authority and the chief priests and scribes, and be put to death, and the third day come again from the dead. And Peter, protesting, said to him, 'Be it far from you, Lord; it is impossible that this will come about'.
But he, turning to Peter, said, 'Get out of my way, Satan: you are a danger to me because your mind is not on the things of God, but on the things of men'."
The name 'Satan' means 'resister', & Peter was resisting what Jesus was telling him, which was God's will for him. Jesus was showing Peter that he needed to listen & accept what he was being taught, rather than serve as a temptation to Jesus. Perhaps Peter just felt that Jesus was feeling low, & was trying to cheer him up. Jesus, however, knew exactly what he was talking about.
The following articles show what actually happened to Jesus, in fulfillment of what he foretold would happen to him:
"Reliving Jesus' Last Days on Earth" http://watchtower.org/e/19980315/article_01.htm
"Jesus' Resurrection on Trial --- Modern Doubters" http://watchtower.org/e/20010315/article_01.htm
These 2 articles explain what part Christ's death has had in the outworking of God's will:
"Mankind's Release From Death" http://watchtower.org/e/lmn/article_08.htm
"Restoration to Life"