Tamia Expecting Second Child

R&B singer Tamia and her NBA star husband Grant Hill are expecting their second child, the couple told PEOPLE.

"I'm happy that the secret is out because it was getting very difficult to hide it," says Tamia, 31, who is four months along. "I performed yesterday and I caught a glimpse of myself in a reflection and I thought, 'Oh no, I'm going to have to talk about this."

Grant, 34, is "thrilled" about the new family addition and daughter Myla, 5, looks forward being "the coolest big sister ever," Tamia says.

The couple wed in 1999 after being introduced by singer Anita Baker while Grant led the Detroit Pistons to the NBA playoffs. He now plays for the Orlando Magic.

Tamia released her fourth studio album Between Friends in 2006 featuring her hit single "Can't Get Enough, " a love song about her husband. Despite her 2003 diagnosis of multiple sclerosis, Tamia says she feels "fine."

"The baby is healthy, everything is great," added Tamia.