What should I do about a Student loan I co-signed that's going to default in 8 days?

I mistakingly co-signed a Chase Student loan for a friend about 3 years ago, not knowing what the terms were, having been mislead thinking I would have nothing to do with paying them back. I realize now that the co-signer is as responsible as the benefactor of the student loan. He has not payed on the loan (he promised me he would consolidate after he graduated), and now Chase Bank is coming after me for payment. They said it would default the 31st of this month if they did not receive payment. They have been calling me everyday, sending letters for collection of payment, and I haven't responded except once or twice to tell them it's not my loan, and I am not going to pay. I told them he forged my name, because I hadn't approved of the $20000 he took out. All I did was say he could use my name and address (not knowing what co-signing meant). Now it is up to 26,000 and ruining my credit. Late fees, interest, and no payments have been made. This guy is unavailable, and when I contacted him via Facebook, he said he would "try and take care of it." I know he won't do anything about it, so what should I do? Im out of a job and have NO money to pay this. Plus, I have my own loans on hold as it is. Someone please help!!!