What do you mean in describing yourself as the "manager"? That could mean anything from a person who lives on site and takes care of an occasional plugged toilet to a "soup to nuts" property management firm that takes care of all aspects of managing and renting the property.
If her problems are valid she could conceivably countersue for a rent abatement.
If you serve a "pay or quit" notice and the tenant pays, then rent is paid and the eviction does not proceed. If the tenant doesn't pay, you can try to get and collect a money judgment. Nobody here can promise that efforts to collect such a judgment will be easy or successful.

