Senora de la Vega could have no interest in betraying me.

She hated her savage husband too heartily to be the voluntary instrument of my destruction, and she was so utterly wretched that I pitied her from my soul.
A creole of pure Spanish blood and noble family, bereft of her husband, forced to become the slave of a brutal Indian, and the constant associate of hardly less brutal women, painfully conscious of her degradation, hopeless of any amendment of her lot, poor Senora de la Vega's fate would have touched the hardest heart.

And she had little children at home! My suspicions vanished even more quickly than they had been conceived, and before I reached my quarters I had decided that, come what might, the attempt should be made.
The next question was how and when.

Clearly, the sooner the better; but whether we had better set off at sunrise or sunset was open to doubt.

By leaving at sunset we should be less easily followed; on the other hand, we should have greater difficulty in finding our way and be sooner missed.