It looks like you are referring to Tommy Castelli, the candy store owner in Bernard Malamud's short story, The Prison.
Tommy Castelli is a reformed juvenile delinquent. At the age of twenty-nine, he finds his life a 'crashing bore.' Tommy is married to the shrewish Rosa and works as the proprietor of a candy store. He is a discontented man, disappointed in the choices he has made and in the circumstances of his present life. His motto is that life is often a harsh taskmaster and that any efforts made to secure happiness and contentment will end in futility. One can say that Tommy often wallows in resentful apathy.
You never really got what you wanted. No matter how hard you tried, you made mistakes and couldn't get past them. You could never see the sky outside or the ocean because you were in a prison, except that nobody called it a prison, and if you did, they didn't know what you were talking about, or they said they didn't. A pall settled on him. He lay motionless, without thought or sympathy for himself or anybody.
While he lives what he thinks is a drudgery of an existence, he discovers that one of his young customers has been stealing candy from him.
He finds himself suddenly concerned about the future fate of this young thief; he worries that if she does not put a stop to her habit, her life will be ruined.
He found himself thinking about the way his life had turned out, and then about this girl, moved that she was so young and a thief. He felt he ought to do something for her, warn her to cut it out before she got trapped and fouled up her life before it got started.
Tommy's attitude highlight his generosity of spirit and his compassion for a young girl's plight. However, being himself a former juvenile delinquent, he doesn't feel comfortable in this new role of 'reformer.' It is 'strange and distasteful to him' and he finds himself worrying about how he will confront the girl with her crimes. He does not feel confident that he will be able to get the message across forcibly and effectively enough to prevent the girl from becoming a repeat offender.
One day, Rosa herself discovers that the girl has been stealing. She is so angry that she shakes the girl violently. Tommy pulls the girl away from his enraged wife, and they get into a little argument. In the end, desperate to retrieve some measure of his self-respect, he strikes Rosa hard in the mouth. The girl's mother comes to retrieve her daughter, but before leaving, the young girl sticks her tongue out at her defender. Although Tommy tries to help the girl, his defeatist attitude, stemming from a life of failure and disappointment, cripples his effectiveness and colors his actions in inconsistency and doubt.