Mother’s Day is the sort of manufactured holiday often cloaked in sentimentality and clichés. Long-stemmed red roses, exorbitantly overpriced brunches, ­cloying greeting-card poetry—all point to a skewed, idealistic view of motherhood. The commercialization of Mother’s Day does a disservice to the endlessly nuanced roles mothers play in all cultures, and the incredibly complex relationship their children have with them.  If Mother’s Day is all chocolates and ­bouquets, then opera’s mothers are contrastingly short-shrifted in another way, almost always portrayed as harridans and manipulators with a penchant for infanticide or suicide. But mostly they are distant, off-stage presences, usually only granted…