Please help! Daughter forced to live in basement and eat flies?

This is the plot of a book that someone I know has posted online. She has searched for 8 years on and off!! And now I need to know too!

Hoping one of you has read it!

The book itself is set around a husband and wife who have two children a girl and a boy who is young enough to still be in a high chair.

The husband becomes convinced that the daughter isn't his biologically so begins to starve her before moving her into a room downstairs, baracaiding her in and just forgets about her until a neighbour sees the little girl eating flies off the window sill and confronts the father who says the child is sick. The father then nails boards over the window. It's set somewhere hot, maybe in summer but definitely in America.
Meanwhile the mother gets drunk, shags a decorator,ignores what's going on and looks after the boy.

It winds up with the family throw a dinner party. the father tells the guests the whimpering they can hear are either puppies or kittens. As you can imagine the whole thing doesn't end well becsuse the little girl dies about 2 hours before police break down the door to rescue her after being tipped off by the neighbour. An officer carries her through the house and the mothers mind snaps and that's the end.

It's a really awful book that I read about 10 years ago and it really gave no indication of what it was about until you were already sucked into it.