Why do you think John Proctor decides to confess? Why does he change his mind? Give evidence for both your answers

At first, it is thought that because John wanted to live, he would most definitely confess to witchcraft, especially considering Elizabeth is pregnant and has other children, whom he wants to be alive and there for. He asks his wife if they are healthy and how the unborn child is going. However, as they deepen in conversation, John becomes unsure of his decision.  He decides to confess, however after writing the paper, he changes his mind as he does not want to be living his life in a lie, it is too much of a sin.  Evidence of this is shown in Act four:
Hatherone cries, “He will confess! Proctor will confess!” 
which is followed by John Proctor replying:
“Why do you cry it? It is evil, is it not? It is evil.”
He is at this stage now very uncertain at what choice he is going to make, and looks to his wife for guidance, however, she replies 'I cannot judge you, John". 
He then decides to confess, and sign the paper, finally understanding what Elizabeth was trying to say to him, which was that he shouldn't not and cannot be able to live with himself lying, and thus stick to the truth and his beliefs, even if it means he will be hanged.