The Glass Heart — Suzanne G. Rogers

After Merrill's widowed mother becomes engaged to an earl, the fate of their respective estates hangs in the balance. A battle of wits ensues when the earl's arrogant son shows up to make demands. Despite their prickly start, once Merrill discovers she and the viscount have both been painfully crossed in love, she begins to feel a measure of empathy. Unfortunately for their burgeoning relationship, a tempestuous drama threatens to tear them apart forever.