Kidder dealt with mental illness for much of her life, while a 1990 vehicle accident left her in debt and needing a wheelchair for nearly two years.
As it was previously reported, the police discovered Margot passed away on the 13th of May in her home in Livingston.
McGuane noted that Montana has one of the highest suicide rates in the nation and she urged people with mental illness to seek help.
Born Margaret Ruth Kidder on October 17, 1948 in Canada's Northwest Territories, she grew up in a small town without a movie theatre.
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Villagers clear debris caused by an quake at Sajang village, Sembalun, East Lombok, Indonesia, Monday, July 30, 2018. Hundreds of tourists are making their way off 12,224ft Mount Rinjani after the 6.4-magnitude tremor on Sunday.
In a statement to the Associated Press, Kidder's daughter Maggie McGuane said the family decided to make her mother's suicide public because "it's important to be open and honest about the suicide so there's no cloud of shame". "It's important to be open and honest so there's not a cloud of shame in dealing with this".
"In her last months, she was herself - same kind of love, same kind of energy", Kesich said.
"It's a very unique sort of grief and pain. She was really a blazing energy".
Diagnosed with bipolar disorder, the actress became an activist for mental health issues as well as a champion of left-wing causes.
Both Kidder and co-star Christopher Reeve, who played Superman, were relative unknowns when they got their leading parts, and neither saw many major roles afterwards. Kidder also appeared on the Smallville TV series, and she most recently appeared on The Neighborhood as Maggie.