Someone transferred money to account for stock market trading

A person called A had transferred 60 lakhs in 2015 to my bank account for the purpose of trading in the stock market. In 2017 his brother invested another 15 lakhs into my bank account. To protect himself he made me sign an agreement that since the bank account and it's associated trading account has only his investments that he will be operating both solely and is responsible for the profits and as his own money he will spend it. This agreement was made on a white paper and signed by the both of us. From 2015-2022 over recurring bank transfers from my bank account to his own and his brothers he has transferred about 50lakhs. This apart he has taken 32 lakhs as cash from me for which he has admitted in a whatsapp chat which I have saved. Now his brother and him have filed a petition using IPC 420 saying i have cheated them and that they want their principal investment back. No where in the agreement have i mentioned that i am responsible for the principal nor have I promised any return