Less than three months after his daughter’s death by suicide , Martin Short is opening up about the toll on his family and the importance of mental health . On Sunday, the 2x Emmy-winning comedian explained that his late daughter Katherine Hartley Short “did the best she could until she couldn’t,” noting that mental illness is just as much a disease as cancer. “It’s been a nightmare for the family,” he said on CBS Sunday Morning . “But the understanding [is] that mental health and cancer, like my wife’s, are both diseases, and sometimes with diseases they are terminal.…