There aren't really any adoptive families out there for 10 year old cats who poop on the floor, so on the advice of our veterinarian and our local no-kill animal shelter, we had her put down today.
I feel horribly guilty. My cats were my first "kids," and now I've had one killed for misbehaving. But cats aren't kids. The ethics are different.
I'm sad now. Josh is probably even sadder. But we gave Tallulah a good life. And that's what I'll choose to remember.