What would some key quotes be during Act IV of The Crucible while John Proctor is confessing?

One of the key quotes you will have to talk about is when John Proctor says:

Because it is my name! Because I cannot have another in my life! Because I lie and sign myself to lies! Because I am not worth the dust on the feet of them that hang! How may I live without my name? I have given you my soul; leave me my name!

This quote occurs after John Proctor has agreed, after much pressure, to save his life by admitting to the crime of witchcraft. The problem comes when he signs his name and he is told that his confession will be posted publicly so everyone can see it. Partly, this protest of his reflects his guilt - he would not be able to live with himself if he signed his name whilst others, like Rebecca Nurse, far worthier than him, died. Also, it reflects the importance of having a good name to belong in the society of Salem. Earlier in the play John Proctor refused to testify against Abigail to protect his name, now we see he comes to a maturer understanding of what having a good name means - he cannot lie to save himself, and is willing to go to the gallows to preserve his good name.