arbitration

hi,i had a huge loss in currency futures trading recently.and my trading was off-line. my invested fund was  not sufficient tp pay the debit.now the broker is asking the money and otherwise they may go to leagal action.but i have no more money to give broker and i feel that they are also responsable for the loss as my trading was offline and they were able to cancel the contract to avoid the loss beyond my invseted fund.pl.advise what to do against the leagal action.