It hurts so much to have to make that decision about a beloved pet, but it is worse to leave them in pain. I always remind myself it is the last act of love we can do for them.
Things are ok here. We have had a lot of things go wrong, mostly out of our control, and we're spending a lot of time (and money) dealing with it all. But everyone is ok, and everything else isn't as important.
It's a coincidence that your cat was 15 - I am also dealing with my own 15 year old cat who has health problems. He's been treated for pancreatitis for months and has finally developed diabetes, so I have to give him insulin twice a day. He's still happy and comfortable and getting into trouble as he always does, and that's why we're doing this - for as long as we have him, we want him to have a good life. But I know he doesn't have much more time, so I'm enjoying having him for as long as I do.