I have a friend who is married and has children. My friend got to know a young man and they loved each other over the internet. Everyone of them lives in a different country and they have never met. By the passage of time, their relationship got strong and they began to practice adultery over the phone. I would like to know what the Islamic ruling is on this? Is what she did considered adultery? If so, what should she do to expiate for her sin, knowing that she no longer chats with that young man and that their relationship is severed. I would like to know whether she has to tell her husband, knowing that she has repented from this sin? Please answer me.

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

All perfect praise is due to Allaah, Who blessed that young girl with repentance. As long as she has repented of that sin; which is having a relationship with a foreign man and practicing sex with him over the phone, Allaah Almighty accepts the repentance of the one who repents to Him if he gives up the sin, regrets doing it, and resolves not to go back to it again. It would be better not to tell her husband or anyone else about what she did. That is because Allaah Almighty likes that the slave conceals his faults. 

What that girl did does not incur corporal punishment; however, it is included in the Zina (adultery/fornication) of the tongue and ear that is to be expiated from by repentance.

Allaah Knows best.