Does anyone know this book?  The hero is a doctor and goes off to the Civil War. The heroine hears of his death. Later she meets someone she thinks she may could love and becomes pregnant. He dumps her instead of marrying her. She then goes back to live with her husband's sister who has always been her friend. She has the baby and then supposed dead husband returns.......then things really get interesting.

don't have a clue but please let me know if you find out the title I would love to read it