I was reading your post and feeling so bad for you.....I was where you are one month ago. And this has not been a good month, it's been a month of doing things I did not want to do, did not think I could do, mourning the loss of ever being able to do anything ever again other than take care of a kitty.
But just doing it one shot at a time and one ear prick at a time, and wandering around various stores with my list of wet cat food showing the carb %, trying to convince all 3 of my cats that they can live without gravy and heavy sauce on their food....because, really, all they ever wanted to do was just lick the good stuff off and turn their noses up at the feed.
But things seem to finally be turning around with my kitty. I do have a good vet and that helps, and having these people really helps, having supportive friends, and having my kitty feel better than he has in a while makes it less horrible. Now he reaches out with his paw and touches my face, something he did not do before. I think that it is both an expression of gratitude because he knows he feels better, and an expression of sympathy for me, because they are sensitive creatures, and know when we are in pain.
As I was reading your post, and the words of advice and encouragement to you, I heard my cat go to the litter box and I jumped up and grabbed my urine testing strips and ran back to steal a sample to test. This is not something I ever, ever thought I would do. I don't think it was even necessary for me to do that at this time, but habits form, and then they become part of the routine.
Everyone here supports you, and no one judges you for your shortcomings...I've got plenty, and pretty sure the other people here do, too. All you can do is your best. It's hard. But it gets easier.....maybe not that much easier, but less overwhelming.