Angelil had surgery last December to have a cancerous tumour removed.
Dion released a statement this morning saying it has been a "difficult and stressful time" trying to fight the disease while raising three young children and balancing her singing career.
She has also been grappling with inflammation in her throat muscles, the statement said, and hasn't been able to perform her scheduled Las Vegas shows since July 29.
All of her performances at the Colosseum at Caesars Palace have been cancelled until further notice.
She will also scrap her tour of Asia, scheduled for the fall.
The statement asked for privacy at this time.
Said the singer: "I want to devote every ounce of my strength and energy to my husband's healing, and to do so, it's important for me to dedicate this time to him and to our children. I also want to apologize to all my fans everywhere, for inconveniencing them, and I thank them so much for their love and support."