Matthew 16:
23: But he turned and said to Peter, "Get behind me, Satan! You are a hindrance to me; for you are not on the side of God, but of men."
John 19
[27] Then he said to the disciple, "Behold, your mother!" And from that hour the disciple took her to his own home.
Right... Mine is selective but yours is not.
Good grief!... Oh, so mine is selective but yours is not.
Let's not confuse rebuke with condemnation. Peter was trying to save Jesus from a certain and terrible fate. This is the same anyone of us mere mortals would do if one we loved dearly chose to die a terrible death. Jesus was focused on his divine mission and regarded anything or any weakness that might deter Him from it to be a message from Satan. The following from NIV, courtesy of Bible Gateway.com
Matthew 16
18And I tell you that you are Peter,[3] and on this rock I will build my church, and the gates of Hades[4] will not overcome it.[5] 19I will give you the keys of the kingdom of heaven; whatever you bind on earth will be[6] bound in heaven, and whatever you loose on earth will be[7] loosed in heaven." 20Then he warned his disciples not to tell anyone that he was the Christ.
21From that time on Jesus began to explain to his disciples that he must go to Jerusalem and suffer many things at the hands of the elders, chief priests and teachers of the law, and that he must be killed and on the third day be raised to life. 22Peter took him aside and began to rebuke him. "Never, Lord!" he said. "This shall never happen to you!" 23Jesus turned and said to Peter, "Get behind me, Satan! You are a stumbling block to me; you do not have in mind the things of God, but the things of men." 24Then Jesus said to his disciples, "If anyone would come after me, he must deny himself and take up his cross and follow me.
**********************************************************************************
Peter did just that. He worked miracles, converted Jews to Christianity, wrote two books of the Holy Bible and died as a martyr in Rome.
As to Jesus bequeathing Mary to the care of John as his Mother, Jesus was looking after Mary’s mortal well being. And you would yours if you were about to depart this world. John was young. Peter was older and already burdened with being head of the Apostles.