dont know what to do

my father passed 6 yrs ago I got on mom and dad credit card sence then my mother has almost maxed her card out 18k I have called the credit card company 20 plus times to tell and explain to them that im not paying her bill if something would happened to her they have said that i would be responsible for it I have not charge anything on it my mother now is thinking about bankruptcy we have the same credit card number can they come after me or make me have bad credit do i have to file with her