Is it permissible for a man to speak with his divorced wife over the phone and via the internet—given that he has a child with her—if their conversations go beyond matters of the child and include her confessing her love for him, and he does not intend to take her back into his custody but fears telling her that lest she harm his son, and he is currently married and has promised his current wife not to take his divorced wife back? And what are the limits of the relationship between a man and his divorced wife in this situation?

If a revocably divorced woman is still in her waiting period, she is considered like a wife, and it is permissible for the husband to speak with her and tell her of his love for her; for this might be an impetus for him to take her back. However, if she is irrevocably divorced, or her waiting period has ended, she is a stranger (non-mahram), and it is not permissible to speak with her except out of necessity, and it is forbidden to speak with her about love and the like. The husband may take back his revocably divorced wife as long as she is in her waiting period, and he is not obligated to be faithful to his second wife with the condition of not taking her back.