Coop Legal Fee Dispute

I live in a COOP building and have made complaints regarding my neighbors noise level. The building attorney reviewed the case and decided the noise is reasonable and not action will be taken. I just got a bill from the building for the legal fees incurred due to the lawyer. When questioned the charges, they told me that "The Proprietary Lease states: Reimbursement of Lessor's Expenses: If the Lessee·shall at any time be in default hereunder and the Lessor shall incur any expense (whether paid, or not) in performing acts which the Lessee is required to perform, or in instituting any action or proceeding based on such default, or defending, or asserting a counterclaim in any action or proceeding brought by the Lessee, the expense thereof to the Lessor, including reasonable attorney’s fees and disbursements, shall be paid by the Lessee to the Lessor, on demand, as additional rent." How do i defend myself?