Harrassment by family

Hi I am under a gr8 trouble and mental harrassment from my own blood brother. I was a student in 2008 took a loan from a bank where my father and brother both where guarantor. 2011 was suppose to be the repayment to start. At that time only my brother was earning . Suddenly after marriage he completely changed and discarded his family in 2011. From the he did not pay the dues to the bank and I also did not have any job. I got job in 2015 with a very nominal salary. Now I have a family spouse one son. Upon this I also have to take care of my old parents who are not well. Bank is behind money and I have a very normal Pvt job. Warning just enough to support my family and my old and sick parents who he has discarded. All responsibility lies on me now. In this situation my brother has even disown any responsibility towards family and his own parents also is sending me legal notice of criminal office and intent to cheat him (which is just a way to escape from any liability that should not come on him ) He is also continuously calling In My office and talking to my manager and supervisor to tarnish my name and harrassment me . He will also lie and try to get information about me from my organisation and reaching to HR. He also call all my family members multiple times at home odd hours and records the conversation and send it to others again giving mental harrassment and tarnishing our family name . I am in deep sorrow that I m in this situation due to my own brother and also as the dues where not paied the amount has gone very high . Pls advise what should I do and how do I handel this .