Barbara Walters is enjoying wonderful highs these days as a host on ABC's 20/20 and

The View, but the veteran TV personality confesses that she's still saddened by memories of her mentally disabled older sister, Jackie.

"When I do interviews with people and people say I make them cry. The only thing that makes me cry is talking about my sister," the 69-year-old legend admits in an upcoming two-hour A&E Biography (Oct. 15, 8 pm). "Maybe it has given me compassion and maybe it makes me understand that things are not black and white. It's only in recent years and since my sister's passed away that we do talk about her, because we didn't tell people; we didn't want anyone to know."

"I felt always enormous guilt," adds Walters, who recently inked a new five-year pact with ABC. "I didn't want to give parties at home because I had this picture of Jackie being in the living room and the party was outside. I didn't want to take her along. I had the love for her and the guilt for her and the hate for her sometimes."

The A&E doc also chronicles her sometimes difficult life with her late father, Lou, a successful nightclub owner with a gambling problem. "What I wanted was a daddy who was a dentist, who came home every night," she says. "I wanted to be home in our house with Ozzie and Harriet."

Longtime pal Joan Marks is likely to surprise many Walters fans when she describes her famous friend as a "very vulnerable" person. "She wants to be not only good, she wants to be the best."