Her secret was working in her ample breast.

Very soon she could contain it no longer, and breaking in upon her husband's parish news, she tumbled it all out pell-mell with a mixture of discomfiture and defiance infinitely diverting.

She could not keep a secret, but she also could not bear to give William an advantage.
William certainly took his advantage.

He did what his wife in her irritation had precisely foreseen that he would do.

He first stared, then fell into a guffaw of laughter, and as soon as he had recovered breath, into a series of unfeeling comments which drove Mrs.Thornburgh to desperation.
'If you will set your mind, my dear, on things we plain folks can do perfectly well without'-- et cetera, et cetera--the husband's point of view can be imagined.