Can a nursing home sue me for my brothers nursing home bill?

As POA I was handling my brothers finances including receiving his social security disaability. A medicaid application was filed and the nursing home was sending me bills for what they said was his portion of his bill. I sent them checks for whatever amount they asked for. THEN, the nursing home calls and says they were billing wrong, he's going to get a large bill in the mail but don't worry he doesn't owe it. Now, I find out that He and I (as POA) are being sued so they can try to collect what he owes. We've filed a bankruptcy for him because his income is $45.00 after paying the nursing home...he'll never be able to pay off the balance. So, they're sueing me too. Am I personally liable for his debt?