Help! Condo owner needs advice. Negligent/filthy neighbor with extensive water damage and rat infestation!?

I own a condo/town home. I noticed water was puddling in my kitchen from under the baseboard of the wall that adjoins my neighbor. I called a plumber out to be sure it wasn’t an issue in my unit. Couldn’t find anything here. Noticed that the next door neighbor’s patio area had a lot of collected water and also mold on the exterior siding. Also noticed what looked like water coming down the window from inside. Rang the doorbell and knocked w/ no answer. Noticed her car parked out front ( she only has one). Got worried and called condo association but couldn’t reach anyone since it’s Saturday. Got really worried after extensive knocking on neighbor’s door and no answer. Called cops. Cops come out and enter home ( back door was unlocked). Cops find home empty but are flabergasted at the state of affairs inside. The entire upstairs bathroom floor had collapsed into the kitchen area with water pouring down walls– entire dining room/kitchen area flooded. Cops also mention extensive mold on walls and rats and roaches running around!! Garbarge everywhere inside. A complete nightmare. The cops said the place needs to be condemned. Finally talk to property management company who seems to think that it’s okay to wait until Monday to do anything. We have our plumber turn off the water outside. A few hours later a water and fire damage restoration company shows up stating they received a call from the unit owner ( landlord). The guy says the tenant has ‘been out of town’ and is supposed to be meeting him there. We inform him of what is going on inside. Tenant shows up in a cab and promptly tells us that she was unaware of any problem and has been out of town since Wednesday. She also mentioned that the landlord was aware of the issue before the condo association called him?? How did he know if she didn’t know?? It’s obvious by the extensive damage inside that this has been an ongoing problem. Not only that but what explains the filth, garbage, and rats?! I need some good advice on what my next steps should be. We are going to file a complaint at city hall and I will be contacting the owner and demanding that he pay for a full inspection of my unit as well as any necessary repairs. I am worried about the health hazard and the potential damage to my structure! Should I seek legal help? Any advice is greatly appreciated.