O'Neal discussed Fawcett's death from cancer last month with NBC News's Meredith Vieira for a "Today" segment set to air Tuesday, NBC said. The interview marks the actor's first since Fawcett died.
"I'm using what she taught me to survive," O'Neal said. "To go on. To care for my son, Redmond. And I have launched into this massive job of answering the mail that has come in for her over the last few weeks. Hundreds and hundreds of letters of pain and sorrow and hope and so I'm answering them. Every one. That's my life now. It's gonna take a while."
Vieira then told O'Neal she could tell he was still "hurting very much."
"She was big. She was big," O'Neal replied, referring to his girlfriend, the mother of his 24-year-old son, Redmond.
2014: The Year in Music [PHOTOS]