In His Brother's Place by Elizabeth Lane

"I want the boy." For three years Angie Montoya hid her son from her late fiancé's family…until his brother tracked them down. Now Jordan Cooper demands she move to his Santa Fe ranch—the boy's birthright. But how can Angie live with the man who called her a gold digger…the man whose one kiss she's never forgotten?

Racked by guilt since his twin's death, Jordan seeks redemption by raising his nephew. But Angie resurrects a hunger in him that only she can satisfy. Jordan knows he can have her on one condition—that she never learns the truth about him.