you've done the right thing letting him see his brother -At least now he knows that his brother is gone, he won't always wonder where he is
One of our cats was hit and killed by a car and we took him and put him in the garage laid out because him and my dad had a really strong bond and we wanted to wait for him to come home from work so he could bury him. The cat's brother was searching everywhere for him and started to get frantic (normally he didn't bother cos the other cat would be out and about late, and he didn't seem to worry).
In the end we took him into the garage and he did the same as Knips rabbit - he sniffed him, briefly licked him and washed his wounds
() then wandered away. I think they understand. He never looked for him again, he just sort of took over the places that his brother used to sit in - I guess he could smell him.
I'm so sorry, it's a horrid way to lose an animal and upsetting to see your other kitty suffering. See how he goes, and if he's really upset, then consider getting a kitten in a few weeks, will help fill the gap and your remaining cat will not feel alone (although he might not accept a newcomer straight away and there may be fisticuffs to begin with). Alternatively, he may just adjust to being a single puss and be fine
Good luck with telling your partner, I wouldn't wish that on anyone. When she arrives home just tell her quickly and let her grieve. Nothing worse than knowing someone is trying to tell you something but is having a hard time doing it.
