Hi Kats
I'm so sorry to hear about Harvey
I lost my Tiger to FIP at only a year old. Once his tummy swelled the end came very quickly
It broke my heart to see my beautiful boy in such an awful state. To begin with the vet wasn't entirely sure it was FIP as he said that liver problems could cause very similar symptoms so they kept him at the vets for a week to monitor him but in the end there was nothing more they could do for him and he was PTS.
They insisted on doing a post-mortem to establish that it was FIP and when it was proved that it was I wasn't allowed to take him home to bury him as they said even with him being under the ground the risk of the disease spreading was too great
Gillian, is quite right when she says that cats don't catch FIP, it's the corona virus they pick up. After Tiger's death I had to have Lily tested and she proved positive but never developed FIP all the years that followed.
My thoughts are with you at this tough time