Meredith Vieira's husband, writer and television news producer Richard Cohen, has lived with multiple sclerosis for the past 30 years and was diagnosed with colon cancer in 1999.

But even though the diseases made him think about leaving his family for their own good, Vieira says she always wanted to stick by him.

"This is my life," she tells Barbara Walters, with whom she co-hosts The View, for an interview airing on ABC's 20/20 at 10 p.m. today.

"She's been there, you know," adds Cohen, who has written a book on the subject, Blindsided: Lifting a Life Above Illness: A Reluctant Memoir.

"And she's seen a lot of bad stuff and she's never wavered," he says. "I'm not the man she married. And I look in the mirror trying to find the man she married sometimes."

Despite the stress of illness, Vieira says her husband is the "greatest teacher" to their three children.

"He's teaching them compassion and strength and dignity, bravery ... humor, incredible humor. Their intelligence is all Richard," she says. "When I read Lily's writing, I see Richard. When I see Gabe's sense of humor, it's Richard. When I see Ben's strength and character, it's Richard. That's what he's giving them."