Scarlet,

I am so sorry for all that you are going through. I totally relate to the depression as well as to the sick pet. I have two cats that are high maintenance...once esp. so. He has heart disease and kidney issues (he's had 3 surgeries) plus a colon issue. Luckily he's feeling good (I do a lot for him, and his vets are amazing) but he's incredibly expensive (insanely so) and about to be 13. I worry constantly, but I love him more than anything else, and he needs me to take care of him.
Do you have a vet school near you? Just wondering if there might be a lower cost alternative that you have not considered, but it sounds like you are doing what you can and considering all the options.
I hope things improve for you, sending you hugs.