Cancelled marriage

hi,

This relates to the cancelled engagement of my nephew. My nephew liked a girl and they were carrying on for some time. But he got engaged to another girl due to  family pressures. Later on we came to know that the girl he got engaged to was not of a very good nature and marrying her would cause problems later on. So his parents decided to call off the engagement. However, the girls side people later on found out about my nephews affair with the other girl and are now threatening to file a case against him and his parents for cheating, i.e not disclosing the facts before the engagement. They are also threatening to defame them by publizing about their affair in the church and are blackmailing him just for nuisance value. They are not interested in continuing the marriage but just want to take revenge for cancelling the marriage.

My questions are:

Does the girls side have any legal recourse against my nephew?

Does my nephew have any legal recourse against them for blackmailing and harassing him and his family?

Please advise. Thanks.