Cat With Scc - Hard Decisions, Confusing Feelings

Hi all, I'm new to the forum and saw so much support and love here that I decided to join, and share some of my thoughts in hope that I might get some understanding and support here.

My dear cat Peaches is 16 years old, and I've had her since I was a little girl. She probably has oral squamous-cell carcinoma (a common cancer of the mouth). The vet has helped me understand that there's no cure and she doesn't have much time left with me, so the best I can do is give her meds for the pain, syringe feed her, and give her all my love until it's time to euthanize her, probably within the next week or two.

I'm really struggling because I can tell that she's in a lot of pain, but she also seems to have decent quality of life -- she still greets me at the door, purrs on my lap, loves belly rubs, snuggles with her sister, sits in windows and sunny spots, etc. But she's also showing a lot of signs of pain and decline. I know it's not time to let her go yet, but I'm having this awful feeling of almost wanting to get it over with so that I don't have to watch her suffer any more, and so that I don't have to keep guessing, "is her happiness greater than her pain? Am I being selfish for sustaining her?" On the other hand, it's also selfish of me to want to end her suffering just to get closure for myself sooner... and of course I'm not looking forward to the day that I wake up without her purring beside me, and come home from work with no demands for belly rubs.

Has anyone else had this awful conflicting-guilt ridden feeling? Did you eventually just know it was time?

Also, has anyone dealt with an SCC cat? At first the syringe feeding was easy, but now she struggles with me more. She still begs and begs for it and gets all excited when I get the a/d out, but then tries to bat my hand away when I actually give her the syringe. It's really torturous for both of us. Has anyone's SCC cat started chewing / licking herself and ripping her hair out? This is also really awful to see, and the vet thinks it's a displaced pain / anxiety response.

Finally, a more existential question... I'm agnostic, and I don't really believe in a "soul" or an "afterlife." For the first time in my life though, I'm finding myself feeling really empty because of this and really just wishing that I honestly believed that Peaches was on her way to a better place. Please, don't try to convert or "save" me, but if you have thoughts or comforting words about this I'd love to hear them.

Any kind words or thoughts you might have would be deeply, deeply appreciated. Thank you.