"It's like I don't live with him physically, but I live with him inside of me," Dion tells ABC News' Deborah Roberts. "I miss him when he was well. I miss him the way that I knew him, without the sickness."
"I saw him suffer and that is the worst," she continues. "Today, for me, I don't wanna say that it's not as hard. It's a different kind of hard."
The "My Heart Will Go On" singer reveals the sweet gesture her three sons -- 15-year-old René-Charles, and 5-year-old twins Nelson and Eddy -- do nightly for their "Papa."
"Every night, we kiss him good night," Dion shares. "Eddie starts. Two fingers, one finger [kissing gesture]. And he said, 'I love you Papa, so much. Happy Easter. Happy Halloween. Happy Christmas. Happy up, Papa. I love you so much. I miss you.'"
Although Dion has been keeping busy since her husband's death -- continuing her Las Vegas residency at Caesars Palace, and preparing to release her new album in August -- she says she is taking things day by day.
"For me, this is so much right now that I don't look at the schedule so much," she admits. "I trust my team and I trust René, he who lives within me, and I do my very best."
The GRAMMY-winning singer also briefly comments on the heartbreaking death of her older brother Daniel -- which happened only two days after Angélil's death, on what would have been Angélil's 74th birthday. Daniel died of cancer, and was 59 years old.
"I said to myself, 'For his birthday, my husband came and got my brother because my brother was too weak to fly on his own,'" Dion says.
During Dion's in-depth interview, airing on Nightline on Wednesday, she also shares her final moments with Angélil. Dion says she told Angélil not to "worry" anymore, and to "leave in peace."
"'You were worrying for my career. You were worrying for the children. You were worrying for everything. It's enough. Do you trust me?'" Dion says she told her husband of 21 years. "'Please do. Trust me. The kids are fine. I'm fine. I promise you we're gonna be OK. Please leave in peace. I don't want you to worry.'"