Diane,
Welcome back. I have missed you. Please take a deep breath, and know this isn't your fault. Your parents know what your son would do, you even told them, but it isn't their fault either. It is your sons, he is sick and needs help, which you nor your parents can give him. Please turn to your HP and go to f2f meetings for more support. I will pray that he gets the money back to your parents before that check clears, they shouldn't be out the money.
Hugs coming to you