Help with sick cats?

My cats are extremely ill with a very bad virus, the likes of which I’ve never seen in an animal before. They’re miserable, and have already been taken to the vet. We were told to boil water as much as possible, and to even turn the shower on as hot as it will go and to close them in the bathroom to help them breathe, because they’re having a lot of trouble doing so.

One of them was given an IV because they can’t eat or drink, and tomorrow will be the third day without food. We were told to call back by then if they still aren’t eating and drinking (and I doubt they will be, because they can’t breathe well enough to do it), so can anyone offer any tips to help make them more comfortable?

I can’t even be in the same room as them for a long time because seeing them like this is giving me anxiety. The steam from boiling water seems to be helping at least a little, but they don’t want to stay in the bathroom. I’m also getting extremely concerned that they aren’t eating or drinking… :( They’re coughing (I think), sneezing, drooling, have eye gunk, etc.

Has anyone else had animals with really, really bad colds? What helped?