After Annie by Anna Quindlen

 Annie Brown is the heart of her family. She and her husband Bill have 4 kids, live in a too-small house, and lead a hectic life. But they're happy. Then one day Annie collapses while making dinner from what turns out to be an aneurysm and nothing is ever the same for the Brown family. After Annie shows how the loss of the woman who held everything together has a devastating impact on the family--and best friend  --she left behind. And what a struggle it is as they learn to cope with the loss and find new happiness.