“Becoming a parent brings you this sadness you never would have known otherwise,” said a dear friend to me on the phone, as I pushed my toddler in her stroller through the sharp wind and shushed my newborn baby, who was zipped up inside my coat in her carrier. And I felt that delicious sense of recognition, of discovering someone else feels the way I feel. And while I don’t wish sadness upon my friends, it is incredible to have a peek into someone else’s tangled thoughts and feelings and find they look a little bit like mine. Before I became a parent, people told me that motherhood would open me up to more joy than I thought possible. But no one mentioned it would also hurt—that the hard times would hurt and the joy itself would hurt, in an aching, stretching sort of way. Kind of like the growing pains of childhood, or the opening pains of early labor, when it’s more of a dull ache. Like when I crawl into my toddler’s bed to wake her up in the morning, and she wraps her arms around…