@AngelofDarkness256 I want to begin by saying that I am so sorry about your rabbit. I totally understand where your emotions are coming from. These are the exact same thoughts and feelings I went through, that I'm still struggling through, when my sister decided to put her deaf bull terrier to sleep.
He was only 7 months, but he was suffering from inflammation of his brain and psychomotor seizures. They were literally eating him alive. It all happened so fast within a single month. I was his main guardian since my sister works day & night shifts every single day. It was extremely difficult to see him going, and help him, through seizures that lasted anywhere from 2 minutes to 3 hours. Some nights I was out in our backyard until 2 a.m. I also felt selfish wanting to keep him around, but I knew he wasn't going to last much longer.
My suggestion to you, in hopes that it helps you a little bit, is that if your rabbit is doing poorly, with no signs of improvement, please consider helping him by letting him rest. BUT if there is/has been improvement, please keep trying to help him. That's what my sister did. She helped her dog as much as she could, but unfortunately, his illnesses were too advanced for us to help him any further.
Feel free to message me if you need someone to talk to. ❤️