Call recording by third party without permission and blackmailing

R/Sir, the question is related to the love of a married man (40 years), and a married woman (35 years). Both were in love and physical relation about 1year period before 9 months.They were talk on all topics as well as adult talking. One day, before about 9 months, nephew son of woman (27 years, unmarried ) took the phone of woman by guise and set on auto recording. He also set his password on call recording app. Again he took the phone guisly and send recording in his phone by Bluetooth.After getting the recording, he sent through WhatsApp the recording to her real aunt /woman and threating her to viral the recording, demanding the money. Initially before 9 months by talking with him, he deny and promise to delete the recording but now he again start to send /whatsapp the recording and threating her aunt to viral the recording, demanding the money. When his uncle go outside the city and found aunt alone, then he send the recording,make pressure on her, threating that I will say to uncle that you are in relation to other person, Perhaps he wants sexual demand to his aunt. Due to this situation man and woman both are in trouble. So kindly guide abot the legal /solution of the problem. Both shall be thankful to you.