I just found out my baby 4 year old cat is going to die in 2 days

2 days ago I brought my baby to the vet because she wasn't eating, they took her bloods and when we got home she was super energetic again and eating/drinking water. We got the results back the day after that said we needed to get an IV and a blood transfusion in emergency. $4000 later, they say that not only does she have CKD, and UTI, but she also has renal lymphoma and it's going to cost $7000 for the blood transfusion and tests and other diagnostics and $6000+ for her first chemotherapy which will only prolong her life for a couple more months. I had to ask my friends for the $4000, I didn't even have $2 in my bank account. And I called 18 different vets and asked about their payment plans and applied to all of them, only to be rejected because I didn't "meet their criteria". I tried to take out an emergency loan, also denied.

So now I feel like I'm killing her because I'm too broke to afford more time with her, and for her to live longer. She's my precious angel, and she always sits and stares at me with the most loving eyes and follows me everywhere. I had a kitten pass away a couple of years ago from FelV and his head was stinky towards the end. I just smelt her head when I kissed her, and her head now has the same smell. I'm absolutely fucking shattered. I keep looking into her eyes and I can't believe she's going to be gone so soon. She seemed so fine up until a couple of days ago. I'm now supposed to book her euthanisation and I just can't because she's still walking around following me and looking at me with the sweetest eyes. She's literally like my child, I raised her from a baby. I hate this fucked up colonial, capitalist society. I hate this world, where people have the resources to keep my cat alive but won't because I don't have enough money. My poor poor angel baby.

What did you guys do to help you get through your pets death? Is there anything you guys wished you did with your cats before they passed that you now regret not doing?