In her first interview since Swayze's Sept. 14 death, Niemi, 53, who was married to the actor for 34 years, will join Elizabeth Edwards and Susan St. James, both of whom suffered the loss of children in accidents.
The discussion will be moderated by California First Lady and Women's Conference host Maria Shriver, who this summer lost her mother Eunice Shriver and uncle Ted Kennedy.
Swayze and Niemi, who met as teenagers while they were both students at his mom's dance studio, shared one of Hollywood's most enduring romances.
Over the years, the couple – both pilots who often flew together and shared a love of horseback riding and the outdoors – developed "an ease," Swayze told PEOPLE in 2007. "We've been partners for a long time."
It was Lisa who proved a "pillar of strength" during the trying past year, her brother-in-law Don told PEOPLE. United in their focus to overcome Swayze's pancreatic cancer and, as ever, spend his last days by each other's sides, the couple maintained a fierce determination right up until Swayze's death.
The Women's Conference 2009, hosted by Shriver and Gov. Arnold Schwarzenegger, gathers more than 100 newsmakers and world opinion leaders with 25,000 women from all walks of life for to be "educated, inspired and empowered to be Architects of Change in their own lives, within their communities and around the world."
The Women's Conference will be streamed live at 8 am PST on Oct. 27 at www.WomensConference.org.
PeopleTV Archive: Patrick Swayze: The Time of His Life