I'm coming here for advice/support, don't know where to turn

[Mossfern]

14 years ago I adopted 3 kittens - really adorable little fellers/gal who grew up to be great friends and frenimies.
Broccoli, Gus and Violet. Broccoli and Gus became best buddies - Broccoli would harass Violet and Gus would protect her honor.
It came to pass that about 3 years ago Gus developed diabetes and I've been medicating him every day since. Their meals centered around his meds. Broccoli, the scamp and harasser, Violet, shy, therefore her name and Gus, the most lovable cat there ever was - a great confidante and emotional support guy, actually checking on people's breathing while they slept - the favorite of the grand kids.

Tragically, Gus succumbed to a huge blood clot in his aorta yesterday morning. I was able to be with him stroking his cheek and holding his paw as he slipped away at the emergency vet.. I'm totally heartbroken and have randomly broken out into tears an sobs throughout the day today.

But this is not the advice I seek.
Broccoli has taken up camp in my bed and will not come downstairs. I think he's in mourning.
What can I do to ameliorate his pain? In all these years he has never spent a day without his brother Gus.
My heart is now twice broken.

I'll entertain any suggestions.

Thanks