Promissory note signed by parents

14 months back I came overseas to start a business and took some money from my friend as he wanted to a sleeping partner in my company but due to the delay in setting up my company he is no longer want’s the partnership and now he is asking for his money not only that now he want double of the amount he gave me since I am not in India he threatened my parents that he will file a police case against me for not returning his money so he forced my parents to sign a promissory note and took post dated cheques from them and only granted 2 months time to return his money back but only after a month he started depositing the cheque in bank Without our knowledge and it got bounced multiple times, since I am the one who owns him money not my parents what can I do here legally, and moreover he is verbally abusing my parents on WhatsApp voice messages and telling my mother And sister On there personal number to do prostitution To return his money or else he will shoot and kill me and my family all this WhatsApp messages and voice notes are available in there WhatsApp phone history so what can be done here to ease the situation.?