So for 19yrs NOTHING HAS HAPPENED TO CO-SIGNER!
And why should anything happen to the co-signer? The loan wasn't for him, it was for you, and it's your responsibility to pay it off.

The lender doesn't care that your father was a drunkard or that he inherited a pile of money or any of that. They've chosen not to pursue him, and they aren't legally obligated to.

You signed a contract taking responsibility for that loan, and you ran out on it. It's not your father's responsibility, and you've no legal recourse to make it so. Man up and pay your bill.