The Price of Guilt — Margaret Yorke

Louise Widdows has been trapped inside an unhappy marriage for decades, struggling to find the strength to leave. Then, seriously injured in a hit-and-run accident, Louise returns home from a long stay in the hospital to find her husband suddenly, and mysteriously, disappeared. So, late into middle age, Louise finds herself suddenly free to begin her life over--and to acknowledge the secret that has been haunting her for years: her son, born out of wedlock and given up at birth. But Louise's husband, Colin, has some secrets of his own, and she hasn't seen the end of him yet.