How does Juana know that the old life is gone forever?

Juana knows the old life is gone forever because they lost it when their son was killed.

Kino has fallen under the spell of the Pearl. People are trying to kill them, neighbours and relatives gossip.

From the text below, you can see that Juana knew the old life had gone forever after Kino had been attacked and killed a man.

"Now, in an instant, Juana knew that the old life was gone forever. A dead man in the path and Kino's knife, dark-bladed beside him, convinced her. All of the

time Juana had been trying to rescue something of the old peace, of the

time before the pearl. But now it was gone, and there was no retrieving

it. And knowing this, she abandoned the past instantly. There was

nothing to do but to save themselves."

Sorry, earlier I was looking at Chapter Six. The quote above comes from Chapter Five.

She knows that the old life was gone forever because there was nothing to do but save themselves. Also because once a person kills a man their life a ruined foreverand their is no going back.