I can’t agree “He/she who cries for another person is weak”. It’s sign of a pure heart. Keep reminding yourself people and things both are temporary. Yes it hurts when someone you know becomes someone you knew. We humans are habituated to make impulsive decisions damaging our own sanity. At the end I can say, anything you give or lose always comes back around in another form.
Stay strong & keep walking. Life never stops for anybody.