Ocean, try not to be frightened. Talk with your vet and be strong for your kitty, who at 17 is a very old soul indeed, and may be hanging on because of your fear. Let your cat pass into the next world peacefully, without anxiety or worrying about you.
Try not to be fearful. You can do this without losing your sobriety. You can handle it. Just remember that all is temporary and beautiful. We bring ourselves sadness when we deny Nature her way. If your cat is tired (and he is) he deserves a peaceful rest and he will rest in peace knowing that you will be okay.
Can you let him go with that...can you tell him not to worry and that you will be all right.
I have had to say goodbye to my beloved pets in the past too. Cats and dogs. It is hard and sad. But there is no avoiding it...only making it as dignified and comforting as possible. I have also always kept their remains in lovely wooden boxes with their names on it, and that way they stay with me. There are places that do that.
There are pet bereavement counselors and we are here too.
I hope you find the courage to face your fear and be there for him as you always have.
Hugs and blessings.