Just divorced last week, and wondering about a practical question

I finally left my husband when I lost my job, because he hadn't tried to look for a job, or done anything to maintain our house, in over a year. Someone in a relationship has to work, and someone has to keep the house and cook the meals. That can be co-operative or you can go with one works and the other keeps the house together. But someone has to do it. Our divorce was final on Friday.

I went to look at a car that was offered on Craigslist in the city where I lived for the last 20 years, and he still does. The car didn't work out, so I stopped by the house we rented. He never locks the door, so I was able to walk right in. The house reeked. Positively reeked. Part of the porch had fallen in. It looked like an episode of Hoarders. I dropped off what I was leaving for him and left.

This is clearly unsafe and unsanitary. I'm worried about him and about our animals. The dog seemed fine but I don't know what happened to the cat. He might just have been out "catting around", or he might have run away like his sister did. :)

Now what should I do? I have several options.

Let him stew in his own filth.

Let the landlord know so he will evict my ex. Landlord is an individual investor and doesn't deserve to have his house destroyed. That would leave ex homeless and God knows what would happen to the animals. I can't take the dog.

Call some sort of social service agency. Who?

Try to talk to his mother, who is a first-class enabler.

I feel responsible for the dog. I feel that the landlord shouldn't have to suffer for renting to us. I was raised with the guiding principal never to do anything that has a negative effect on anyone else. I am worried about my ex because he's probably too miserable to see his way out of the mess. He would never clean when I lived with him. It was "too overwhelming".

Anyone have any suggestions? I'm guessing it would cost at least $5000 to make the house suitable for a new tenant. the floors will all need to be replaced (hardwood), and probably the walls too because of the prevasiveness of the smell. I am devastated to know I was married to a man who could live like that.