You can sue your aunt for the unpaid rent, but since this was a verbal agreement, it may be difficult to prove your case since in court it would be your word against hers.  You can file your lawsuit in Small Claims Court.  Your damages (the amount you are seeking to recover) would include the unpaid rent and court costs.  Court costs would include the court filing fee and process server fee.Since your name is on the lease, you would be liable for the rent owed to the landlord.  Some leases prohibit a sublease.  If your lease did not prohibit a sublease and if the agreement with your aunt had been in writing, the landlord could sue either you or your aunt for the rent.; however, since you only had a verbal agreement with your aunt and you are the only one on the lease, you are liable for the rent as mentioned above.