Im in a similar situation with my mother in law. We actually have a family cat named Oblivion, and if you've came across me ever mentioning him before, you know that cat is literally a demon incarnate if he cant exercise enough- meaning he has to go outside. Oblivion lives with my mother in law right now, while ken and I are in an apartment with the dog, some fish, and soon, the bird. Oblivion will come back to our household when I know we'll have a yard for him to play in, but the apartment has an adamant policy on strays.
We would not have gotten the apartment, had we not had assurance that Oblivion would be OK there. We adopted him from a shelter it just seems so messed up to take him back now that he's a snot, not adorable kitten.
Our sister in law, who lives across the street from our mother law, is now trying to condemn our cat, but our brothers cat as well to the streets due to a flea infestation that occurred recently. It's been resolved and I'm offering to mail them flea medication directly, so this doesn't happen again, as well as any additional treatments they may need for the carpets/furniture.
We're not having it, but it's a threat looming around atm. The fact is, she doesn't live in that house. My brother and mother in law do, and mom is disabled. (She had a stroke and lost a lot of motor function, as well as her ability to speak) and she's has bonded to the cat after her Maltese passed away. Oblivion happens to be her favorite, even though he's a little pain. It's not her decision to make, and she's just being a controlling B-... lady.
Felix is innocent in this matter. He's a good, sweet cat, and was hit by a car last time he was on the streets (Which is why we adopted him. He's actually a 'shop cat' for the family business.) There is NO WAY we are sending him back, especially now that he's afraid of cars.
So trust me, I get that.
Oblivion is not an ESA.
That cat is the antithesis of an ESA.
That cat is misery.
I love that stupid cat.