If the family actually signed a sublease agreement, you could collect from them. However, if they didn’t, you are legally responsible for the remainder of the lease.

So, unfortunately, there is little you can do.

. Well, the “2 business days” is probably an empty threat. But you DEFINITELY have to talk to the apt. management! You certainly owe them the $1600 for rent. Give them a check for that on Monday to show Good Faith. I don’t know about the $1400 misc.
I suppose you could sue the couple who backed out of the deal, but legal stuff is expensive and time-consuming. I’d pay the whole thing [under protest] to protect your credit, maybe try to get some back later, and chalk it up to experience. It won’t be the last time you get skrewed. .

Things to check, the family filled out an application form. Did they sign a contract rather than just applying? Was their offer to be the tenants accepted by you or the office? If their offer of tenancy was not accepted then they don’t have any legal responsibility.

Second, the amount of money you are being chased for, is this written down anywhere? Did you agree to these terms? They sound like very unreasonable terms and don’t seem to be general terms in a sublet agreement. If you didn’t sign anything to accept these terms then they can’t force you to pay. If you did sign a sublet agreement and these terms were hidden in the contract and were not bought specifically to your attention then you can contest. Even though you signed (if you did sign such a contract) but can prove that these crazy amounts are not part of a reasonable rental industry sublet agreement then the court can strike them down. If terms are unique to this contract and are not part of a standard accepted rental agreement then the rental company has to highlight these terms outside of the agreement.

Check what you signed and then seek legal assistance.

You might be able to get out of some or all of the fees, but sounds like you are stuck for the rent. You had a lease, and didn’t fulfill it, so you are liable for that much.