Guarantor for secured load from bank by my brother

My name is Suman Arora. I was guarantor for a loan of Rs. 800000/- granted by Bassein Catholic Co-op Bank Ltd. to my Brother on 8.2.2018. Loan was granted against mortgage of property. He continued paying EMI of Rs. 11478/- for eight nine months and thereafter discontinued. Bank has sent letter to my Company through Speed Post for salary deduction towards repayment of loan instalment. Had given guarantee because I was told there will not be any financial liability on me as guarantor because property is mortgaged and in case of default Bank can confiscate property and recover loan amount. My relation with my brother has gone bad. It was good when he had taken loan. Please help me how do I proceed. Thanks & regards SUMAN