I Was A Beneficiary On My Step Dads Account And Now His Bank Is Contacting Me

so my step dad recently passed away, which we kind of knew what was coming, but he told me that if anything ever happens to take the money out of his account and use it to get an apartment which is what i did. Now the bank is contacting me because the social security administration is contacting them saying they want their money back. besides using some of it to get an apartment i was in charge of closing his accounts and paying his remaining bills. I don't have money to pay them back and I'm scared as hell. any advice on the matter would be greatly appreciated