Your best chance here is probably to negotiate with zazarb. Otherwise this scam accusation is probably going to go on forever.

If you can't afford repayment then just say so, instead of going on with excuses of bitcoin being too high or whatever.

Why didn't you just take out a loan fixed in USD if you didn't want to pay off the loan in BTC? Even get a cash advance from your bank/credit card if that's the case. Your deal with zazarb doesn't say anything about the loan being in USD whatsoever.

As yahoo said, speak with zazarb, see if he could offer to lock the repayment amount in fiat now, since bitcoin is quite low at the moment. Or discuss whether you could go on a payment plan without interest for a while.