If thats the case, im really screwed because probate takes forever.Everyone warns me not to touch the apartment.     

Be warned, it is getting harder and harder to cash flow in San Antonio.

Instead of wasting your money you might want to print out the harmful effect of not replacing the filter for residents and make sure the tenants always get a copy and warning,     Also you can take it a step further and you can-write it in the lease that "if the filters are not replaced regularly tenant understand that this will cause a $300 repair bill at the end of tenancy, where tech or HVAC cleaning co. needs to come out and clean the system."

WARNING!

Usually when I get a call from an investor spouting their criteria I delete them from me database immediately and send out a warning to colleagues...not saying you're doing that, but focus in on a couple of markets and locate the top 1% of agents/brokers...establish weekly calls and make sure you're pre-approved and ready to pull the trigger.

WARNING!

In speaking to you, I am trying to sound an earnest warning tone for others.

The fact though that they were warned about the rats should have been a sign that this isn't going to work out but this seems to have spiraled quickly. 

Otherwise simply evict them after a couple of written warnings. 

First off, I've got to warn you about using the BiggerPockets Rental Property Calculator.