Martin Short has opened up about the tragic suicide of his daughter Katherine Hartley Short at 42 less than three months ago, saying her loss has 'been a nightmare' for all who loved her while sharing a poignant message about mental health.

Katherine died in February from a self-inflicted gunshot wound, authorities with the Los Angeles Police Department confirmed in February.

Short, 76, spoke with CBS Sunday Mornings about the family tragedy, comparing her battle with mental health to that of the 2010 death of his wife Nancy Dolman, who passed away from cancer.

'The understanding [is] that mental health and cancer, like my wife's, are both diseases, and sometimes with diseases they are terminal,' said the star of Father of the Bride, Three Amigos! and Only Murders in the Building.

He continued: 'My daughter fought for a long time with extreme mental health, borderline personality disorder, other things, and did the best she could until she couldn't.'

Short said his aim was to support a mental health awareness organization founded by Glenn Close called Bringchange2mind. 

He said the nonprofit aims to take 'mental health out of the shadows' and conduct frank discussions on the important topics at hand. 

Short shared a moving message that touched on how he hopes struggles with mental health can be understood. 

'Not being ashamed of it, not hiding from the word suicide, but accepting that this can be the last stage of an illness - and that’s my approach to this,' he said. 

The Canadian-born actor and comedian detailed how he had been faced with tragedy while growing up and how it had affected him.

He lost his older brother in a car crash when he was 12 and both his parents died when he was a teenager.

His mother, Short told People on May 7 in Los Angeles, died from cancer three years after his brother passed and his father followed her to his grave a year later.

'What it developed in me was this muscle of survival and handling grief and a perspective on it,' he explained.

'We have to celebrate and be lucky enough the experiences that we've had with them.'

He added that he likes to think of those he loses as being 'just gone into the next room for a while.' 

Katherine was one of three children whom Short and his wife Nancy adopted during their long marriage.

Katherine was a licensed clinical social worker with a master’s degree from the University of Southern California 

Her loss 'devastated' the actor and her brothers Oliver Patrick, 39, and Henry Hayter, 36, a representative for the family said in February following the announcement of her death.

But his experience with bereavement gave Short took a poignant perspective on his daughter's decision to end her life.

When his wife Nancy was dying from ovarian cancer in 2010 at the age of 58, her last words to him, he said, were 'Marty let me go'. 

He told CBS Sunday Mornings that to his mind, his daughter Katherine was just in her own way saying, "Dad, let me go."'

His daughter's passing came just weeks after the death of his friend and collaborator of five-decades Catherine O'Hara and two months after the murders of his close friends Rob and Michele Reiner.

O'Hara died from a pulmonary embolism at 71 on January 30, with rectal cancer identified as the underlying long-term cause.

The celebrated actress is featured in Short's upcoming Netflix documentary Marty: Life Is Short.

Directed by Lawrence Kasdan, it's a reflection on his life and work and includes never-before-seen home movies, classic clips of his work and new interviews with his friends and famous co-stars.

Short's appearance on CBS Sunday Mornings was part of his promotional tour for the documentary that drops on Netflix this Tuesday May 12.

Officials with the Los Angeles County Medical Examiner's Office