Yes, Hera did, in fact, throw Hephaestus off the mountain but that wasn't because of Zeus' affairs. Hephaestus is Hera's own child and she threw him because he wasn't exactly handsome. At least that's what Homer says. :)
She was very jealous of the women who her husband slept with in addition to her, and would inflict horrible punishments on them, no matter what their innocence.