This is tragic. I'm sending you tons of p.e. (positive energy) and singing that silly song..."the cat came back, the very next day..." I'm lighting candles. Honestly, sometimes I communicate better/speak the language of cats better than people and until the passing of my cat considered my cat my best friend/baby (I don't desire human ones). I hope Sebastian has a homing device, the way pigeons do. Losing a cat is different than losing a bird (I've had a few a-wol expensive birds in my day).
So, in my non-traditional way of praying, I'm hoping that everything turns out okay, really really really SOON.