I have a problem regarding with the Loan of my partner's friend named xxx. He asked my partner if I can be his co-maker year May 29, 2014. After 2 years dated May 21, 2016 I received a demand letter stating that I'm the one who is responsible to pay the remaining balance of xxx including the said interest. What will I am going to do? I am liable to pay even though I'm only a co-maker? Please response immediately. Thanks!