For 328 days, Rachel Goldberg-Polin couldn’t bring herself to visit the last place where her son knew freedom. Hersh Goldberg-Polin, his arm blown off by a grenade , was abducted from the Nova music festival in South Israel’s Negev desert during the Hamas massacre of Oct. 7, 2023. “I initially said, ‘No, I don’t want to go there,'” his mother, whose book, “ When We See You Again ” (Random House), is out now, told The Post. “It was just excruciating.” But on Aug. 30, 2024, the American-Israeli