Can I, as my father's power-of-attorney, be sued for not giving my father's ex-wife his american airlines account and password?

My father's ex wife has been demanding my father's American Airlines account number and password. American Airlines discovered she illegally used his account to fly herself, her sister, her nephew and two other people on several domestic and international flights, they notified our family and removed her from his account. My family has had to change the password repeatedly due to hacking into his account for the past 2 1/2 years. We have received several persistent and harassing accusations that she is owed these flight passes.They were divorced in 2012 in a different state. The tickets were not part of the divorce agreement, there is no verbal or written agreement. She claims she will sue me for breach of contract, as I am the power-of-attorney for my father. My father has since moved into another state. Can she sue me? And how do I stop her from harassing my family?