Shopaholic and Sister by Sophie Kinsella

Becky thought being married to Luke Brandon would be one big Tiffany box of happiness. But to be honest, it's not quite as dreamy as she'd hoped. The trouble started on honeymoon, when she told Luke the tiniest little fib, about the teeniest little purchase. Now she's on a strict budget, she doesn't have a job - and worst of all her beloved Suze has a new best friend. Then she receives some incredible news. She has a long-lost sister! Becky has never been more excited. Finally, a real sister! They'll have so much in common! They can go shopping together...choose shoes together...have manicures together...Until she meets her - and gets the shock of her life. It can't be true. Surely Becky Bloomwood's long-lost sister can't...hate shopping?