Liability for deceased Wife's Debt

[jhverdery]

My Wife of 42 years passed away last month. She died intestate as all of our assets were jointly held and I am in the process of removing her name from all joint accounts, deeds, titles, etc. But, I have discovered that she had two credit cards in her name alone with a total of almost $36,000 owed on the two of them. She apparently used the money to help bail out her older sister repeatedly over the years. (My wife handled all of the family finances for over thirty years so I was clueless.) If I determine that my name does not appear as a user on these cards, am I liable for her debts? If not, how do I handle communication of this to the credit card companies and if these debts are not paid, will they affect my credit?