It is haram to take a loan on the basis of riba; the one who does this has to repent to Allah, may He be exalted, but he does not have to return anything except the capital. As for the interest (riba), he does not have to pay it and he can use a trick to avoid paying it so long as this will not result in harm for him.
You have to return the loan to the bank by any possible means, and it is not acceptable for you to give the money in charity, because giving the money in charity is only an option when the owner or the one to whom it rightfully belongs is not known, or it is not possible to send it to him, in which case you may give it in charity on the basis that if you find the rightful owner, you will give him the choice between approving of the charity or taking his due.
The bank is the rightful owner in this case, and is known. So you have to return the money to it and you have to look for a means that will let you avoid questioning and punishment.
And Allah knows best.