Calling off from Engagement

Hello , After my engagement function that girl was not talking to me, I used to call her but she refused to take my calls or by any chance (because of family member) if she take my called she don't respond me properly. after few days we were chating on phone she told me that she dont want to marry with me, (just for your information, I don't looks good) and after a long chat she told me she already has boy friend. I have told every thing to my family member and we have decided to break up with this relationship. I dont know what discussion is going in his family but her family member asking us to give in written (Affidavit, for girl's security) that we are breaking up the engagement we have not yet returned there gift because we dont want to go to her place we are worried they can create violence or they can do anything. does it make sense ? ok if we give something on written what they can do . we are panning to give something valid and generic reason that , "because of some miss - understanding between us we are breaking up the engagement with the agreement of both the family we are canceling the engagement" will we get in trouble in the future after giving this letter from our side ? what could be the side effect of this affidavit ? what is going on in there mind we are totally blind . we really need your good and expert suggestion. Thanks a lot . Regards.