The Barber's Wife by Tanya Nichols

Back in the day O.C. Holloway and Charlie Floyd were good friends hanging out in rural Oklahoma.  O.C. learns to be a barber, meets Mayme while she was in nursing school, falls in love and makes a comfortable if not very exciting life in Mayme's hometown.  Charlie becomes "Pretty Boy" Floyd. Although they choose very different paths, they connect again as Charlie and a few other unsavory characters secretly seek help from Mayme for various health issues.  When Mayme is forced to draw Joe, the local doctor, into helping Charlie, the story takes a very different turn.  Joe keeps Mayme's secret because he is secretly in love with her.  So many secrets to keep in rural Oklahoma in the 30's.  So many moral dilemma's - some resolved at the point of a gun.