How can i complain against a private money lender

Respected Sir, In march 2012 I had taken a loan of 8 lakhs through a known person. This known person had told me that he has taken the loan money from a money lender and i will have to pay 5% interest every month(i.e Rs 40000/-). I had taken this money as my husband had started a new business(a manufacturing unit) and had invested all his life time savings in it. I was hopeful that within a year or so his business will pick up and i will be able to repay the money that i had taken on interest. I had given 3 blank cheques and also signed on a stamp paper. However, i could not read what was written on the stamp paper as it was in Gujararti which i cannot read. I had signed on the last page of that agreement and this known friend also signed on that same page. The entire process from the signing part, giving me the money and collection of interest etc was done by this known person. It has been four years now that i am paying the interest regularly but now situation is too critical for me. My husband's company had to be shut down and we have lost everything. Even our house mortgaged with the bank. I am just not in a condition to pay the interest now. I calculated that i have paid almost 19 lakhs as interest only and the loan amount is still as it is. I have never met the person who has given me the loan. I only hear about him from this know person who calls me and whenever i am late in paying the interest, he tells me that pl arrange the money asap as the lenders are creating problem. I just don;t know what to do. I feel very scared as i don;t know what they will do to my family. I had a small business of my own but i had to close that also as i was unable to bear the office expenses. Pl advise me what i can do. Is there any one who can help me. I get so depressed that i feel i ll commit suicide.