Legal advise sought by senior citizen

It is a case of Cheating /scam.I was contacted by a chat friend from USA for investment in a business. As I was not financially sound, I discussed with a friend who later showed interest. I told him that she is just a chat friend and I have never met her so he should confirm all details before investing any money. He agreed and talked with her .She introduced an American person owing a pharma company to him and he started investing. After some time he realized that he was being cheated and business person & Chat friend stopped calling him. Now my friend behaves like an enemy and asking me to pay his money as I Introduced chat friend to him. He comes to my house frequently and curse me,abuse me , pressurizes me to pay his money. I am already a poor retired person ,Senior citizen 65+ and not keeping good health. I am in a state of depression. He never transferred any money to my account but asking me to pay money.Kindly suggest what can I do to overcome present mess.