I made one unforgivable mistake when I was in North Vietnam, and I will go to my grave with this,” Jane Fonda says on the Oprah Winfrey Network. The actress and activist made an infamous trip to North Vietnam in 1972 where she was photographed singing with members of the North Vietnamese military as she sat on an anti-aircraft gun. She was criticized then — and ever since — and says she understands the anger. Fonda says she knew immediately she had made a mistake and has apologized repeatedly, both privately and publicly. She told OWN program “Oprah’s Master Class”...