Honestly, that sucks man... I'm an avid pet lover and I totally understand how you feel.. I've avoided having pets while travelling just because losing that connection/bond is so very painful. Instead, I now have 3 pets, all of whom seem to have found me as strays.
My recommendation would be one of two things:
1) Mourn him.. Give him a proper burial somewhere nice and just remember that you made his life a happy one and he was surely appreciative of you. Maybe now is not the best time to have a pet, and wait it out for awhile until you feel better.
2) Mourn him.. Again, a proper burial and sendoff; but then go to your nearest animal shelter and adopt a stray. A cat that would otherwise be put down or put into harms way. Do this in a way to not only remember your cat, but to give something in his memory. By adopting another cat, and giving him a meaningful life outside of a cage, you make a sad but very natural occurrence in all of our lives (we all die, bro) have a greater meaning and purpose.
At a minimum, give something to your local ASPCA, anything, for all those pets and animals that didn't have as loving a family as your late pet did.