How have Elizabeth and John Proctor come to terms in The Crucible? Explain the irony in their reconcilement. Why won't Elizabeth be hanged?

John and Elizabeth Proctor are only truly reconciled when they both confess their sins to each other. John confesses his illicit affair with Abigail Williams, and Elizabeth, in a line which has had feminists' blood boiling ever since it was written, blames herself for John's philandering:

Suspicion kissed you when I did; I never knew how to say my love. It were a cold house I kept.

It is only by being completely truthful with each other that some degree of reconciliation has been brought about. Yet the irony here is that it's all too late; the truth no longer has the saving power it once had.
Had John and Elizabeth been honest sooner, they would've saved themselves and many other people an awful lot of trouble. Earlier on, John had the opportunity to confess his affair with Abby but chose not to, as he didn't want to damage his good name and reputation. As for Elizabeth, she had the chance to tell the court of John's adultery, thus exposing Abby as a liar and ending the witch-hunts once and for all. But she didn't. Instead, this normally honest, upstanding woman chose to lie for the same reason as her husband: to protect the Proctor name.
As a result of the Proctors's inability to tell the truth until it's too late, they're both condemned to hang as witches. However, Elizabeth is spared the gallows—as she's pregnant.