Can the co borrower still sue me if I filed bankruptcy on a car loan?

I am a single mother of 3, I had a car loan with my ex's mother, she was the co signer. The loan even with her as a co signer was at 22% the payment was $390 a month, I cannot afford to pay that I am 3 months behind, and the car company is close to repossesion, If I filed bankruptcy on this loan, can the co borrower sue me for the difference even if I filed a bankruptcy or does a bankruptcy remove me from liability on the vehicle.... The loan company refuses to work with me, I ve tried to get them to lower payments, but they wont, its 8 years old, with 120,000 miles on it and there is still more then 11,000 on the loan..... Someone please help, I m tired of being threatenend by the co borrower and her attorney!!!!!