求助：Tenant hired lawyer to terminate the lease

The property is located in Plano, TX. The tenant asked for rent deduction several times and I checked with real estate agency and been advised the rent is in line with market and contact is not expired yet, still 6 months to go. Got a letter from the tenant’s lawyer to terminate the contact.
Please urgently help if you know what I should do or you know any good lawyers in the region. I am currently living oversee. Thanks!