My baby got lymphoma and I’m a mess.

Hi everyone, a week ago we took my sweet baby cowboy to the vet because we noticed he was breathing hard. They did X-rays and found fluid all around his lungs, they drained his chest and sent fluid to a pathologist so we could get an idea what was causing it. We adopted cowboy from a shelter where they’re supposed to test for felv and we got his vaccination not long after we adopted him but we had no record of his test so the vet wanted to run one again. His test came back positive and a few days later the pathologist said they found a lot of cells in his chest fluid so we’re fairly certain it’s lymphoma. Since we got back home he’s been not the same cat and I feel like declining every day. We started steroids because his cancer is likely so advanced we didn’t want to put him through everything to diagnose his specific type of cancer and unfortunately we can’t afford the long term chemo treatments too. We wanted at least a few more good weeks with him hoping the steroids would work but over the last day I’ve noticed such a decline in him. I woke up and he didn’t go to his litter box to go potty he was in the same spot he went to sleep in, I noticed his breathing is getting the slightest bit heavy again, he’s refusing any food now and he’s just laying there. He’s alert and looking around so I know he’s there but it’s. Breaking my heart. He has a check up in 2 days but I feel like they’re going to tell me it’s time and I’m having such a hard time coping with it. I guess I want to know anyone in similar situations how have you known it’s time? I don’t know what to do and I’m so heartbroken hes only a year old :(