How do I deal with my righteous husband who receives lewd pictures from his friend, and is saddened by it, yet refuses to cut ties with him?

Congratulations on having a righteous husband. The Prophet, peace and blessings be upon him, clarified the virtue of a wife who helps her husband in matters of his faith and his Hereafter. Therefore, you must strive to guide him, advise him, encourage him to do good deeds, associate with righteous people, and abandon the company of evil companions. Repeat your reminders, advice, and encouragement for him to listen to beneficial tapes and to associate with righteous people. Increase your supplications to Allah for his guidance. You should also provide him with engaging conversations, entertainment, and companionship that will distract him from negative thoughts.