Where to take cat I'm no longer able to care for?

Hello, I unfortunately have a 15 year old cat I'm no longer able to keep. She's had some medical problems that we've worked through before, but over the past year she's begun urinating virtually everywhere. She's always had the occasional peeing in the closet, but lately she's been ruining things left and right. Closets, clothes, towels, carpet, blankets, furniture. We even got two new couches, and within a week they began to smell of urine, enough for close family to point out. The vet had no medical explanation, and the issue's been around for a hear or so and has only gotten progressively worse. We're moving into a smaller appartment until our new house gets fixed up, and as such this is an immense concern for us. The complex also has a two person limit (as most seem to around here), and we have one other cat and a dog.

I can't bear the thought of taking her somewhere she'd either be uthinized or mistreated. Is there anywhere that I could take her that won't uthinize her and could be a suitable living environment? I've tried places like Craigslist, but the concern of animal abusers and dog fighters has deterred me as I have no interest in accepting money for her

I appreciate any help!