I apologize for not posting a bunch of happy stuff before this.

I took Ziva to the vet today because she has a cold and hasn't been eating well.

Turns out that yes, she has a cold. But Ziva almost certainly, but not 100%, has FIP. I have to decide whether to run $300 of tests on her, or if the evidence of the straw-coloured, thick fluid (classically consistent with FIP, but as I said, not 100%) is enough to indicate that she has FIP and is too sick to save. If it's not FIP, it could be either liver cancer, a liver obstruction, or a massive infection. Fluid is leaking into her chest as well. Our poor little girl is so sick, she doesn't want to walk around or play. She just wants to be left on her blanket to rest. I have to decide this by 5 today, so I can let the vet know whether to mail the sample to the lab or not.

Not fair. Not fair at all.
How am I supposed to make this decision?

EDIT - 6:30pm: Thanks to everyone for the kind comments. It turns out I didn't get to make a decision. When I checked on Ziva at 5, she hadn't moved at all and didn't want to move around or even stand up. When I patted her or picked her up, she cried. We took her to the vet for the last time tonight. When she was gone the vet checked her belly and that she was sure it was FIP, and that she was glad we were able to get her in tonight, because she was in really bad shape. So I guess we did the right thing. It just bites.