"My mom and my sister recently purchased a puppy off of Craigslist..." The common start to such stories, ending unhappily. "we were told that...

Moving to landlord/tenant, which is more appropriate. Evict him.

"My mother has had my dog for the last several years as an emotional support dog." All of which indicates it was her dog, and no longer yours.

It is your friend's issue. She is free to contact the shelter which provided it to Pet Smart and pursue her remedies.

Moving to domestic violence, where this belongs. How is it an EX-bf can even enter your home, still less videotape you in it?

Did you notify animal control you'd found a dog? Did they notify AC they'd lost one, and/or post notices? Did you register and vaccinate the...

No. Evict him properly. If "he's back on drugs," the police may solve the problem for you.

Take it to a shop and have it tested.

If their dogs enter your property, they are trespassing. If they attack your dog on your property, your neighbor is liable. If your dog defends...

Pay nothing without obtaining a full, mutual release. Indeed, pay nothing without documentation of the vet bills and where your dog was when the...