How do you cope with anticipatory grief?

Three years ago, I adopted a 15 year old cat named Suzy. Her owner had died and the family was looking for a person they could trust with her precious kitty. I was looking to adopt a second cat at the time so I volunteered.

From the start, I was surprised at how alert and agile she was for a cat her age. She's the boss of the house, even the dog is a little afraid of her. I love having her around. She isn't really friends with the other animals of the home, but she's very cuddly with humans.

Last September, she was diagnosed with CKD and put on a renal diet. Since then, I've been dealing with a low grade anxiety that each little health event might be fatal, that each vet visit could be the last. I dread the day I will need to take the decision to put her down. It feels like I'll never be ready and I'm afraid I won't be able to make the right decision at the right time because of it. I'm getting emotional just writing this.

My question is: how do you cope with all this? What things are helping you when you go through moments like these? Any advice is appreciated.

Thanks! <3