Will I be able to sue a former tenant after termination?

[David Deng]

I rent out an old duplex in MA and our tenant's dog have been an absolute nightmare for the past 6 months, pooping and peeing on floors, basically using the kitchen and upstairs bedrooms as toilets. This will likely result in thousands in damages to tens of thousands if everything with urine from subflooring to joists have to be replaced.

The tenant signed a termination agreement (I haven't signed yet) agreeing to leave as soon as possible. However, due to the high amount of damages that won't be fully covered with the security deposit, I am thinking that it is worth it to sue for the damages after the tenant has left.

However I have a mutual release clause in the termination agreement:

On the Termination Date, Landlord and Tenant shall be fully and unconditionally released and discharged from all claims and obligations arising out of the Lease Agreement.

Is it a mistake to put this clause in if I am planning on suing after the tenant leaves? Can I still sue for pet damages if there is such a clause on the termination agreement? Is it even worth it? If I can sue, how should I go about doing so? Been a landlord for a few years now but never had problems get so bad that I needed to sue. 

Let me know if any additional information from the lease or termination agreement is needed. Any help will be appreciated. Thanks!