Please help me decide if I should put my cat to sleep.?

My cat is pretty old. I've had her for 23 years now but she got really sick, really fast. Here's a list of her problems: *Severe Kidney Disease *Hyperthyroidism which causes her to eat/drink constantly but still lose weight. She only weighs 4.5 pounds now. I can feel her bones. *There's something pushing her... show more My cat is pretty old. I've had her for 23 years now but she got really sick, really fast. Here's a list of her problems:

*Severe Kidney Disease
*Hyperthyroidism which causes her to eat/drink constantly but still lose weight. She only weighs 4.5 pounds now. I can feel her bones.
*There's something pushing her eye out of socket. The vet believes this to be a tumor
*Urinary tract infection
*Abcess tooth/rotten teeth
*She tries not to put too much weight on her back right leg but she can still walk and jump
*When she breathes, she sounds like she's snoring
*She is losing her hearing

I love my cat so much and I just cry at the thought of not having her with me anymore but I know I have to do what's best for her. The vet says that she's too old for any kind of treatment and that I should just try to keep her happy and comfortable but they didn't tell me to put her down. What should I do?
Update: If she is in pain, I will put her down. I don't want her to suffer because I don't want to let her go. That would be selfish of me and this is about her, not me. As for quality of life, she sleeps a lot and just wants to eat when she's not sleeping. She doesn't play much anymore. She just hangs... show more If she is in pain, I will put her down. I don't want her to suffer because I don't want to let her go. That would be selfish of me and this is about her, not me.

As for quality of life, she sleeps a lot and just wants to eat when she's not sleeping. She doesn't play much anymore. She just hangs out and climbs in our laps when she's ready for snuggles.

I know that no one can tell me what to do. I was hoping to hear what you would do if you were in my position. Thank you so much for your answers.
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