My friend is blackmailing me... Help

I had a best friend... P.s not a boyfriend. He did love me a lot but I never said him that I will marry him... In fact I told this to his mom too... He was a very possessive and a stalker kind of person Now few months back it was a very emotional time and we both got little physical not sex! But still there was no kind of commitment given to him Now after so much of possessiveness and stalking behaviour I stopped talking to him... He is blackmailing me now that he 'll call my dad and my bf that I did all this with him.... (He has no pics of us) He said your father is strict I will tell him anything he 'll beat the shit out of you... And if I call your bf he 'll breakup with you.... And if you don want any blackmailing talk to me.... The proof he is using is our whatsapp chat ...... I have a recording of his and my conversation in which he said he 'll blackmail me... Here the problem... I can't tell my parents nor my bf.... Pls help me... This is a suicidal torture.... If you say police case .. that again will include my parents pls help me