I miss my kitty

On December 11, 2018, my 16 year old cat, Little Brother, passed away during surgery for his teeth--vets then discovered a tumor in his jaw. I am absolutely devastated about this loss. I was 6 when I got him, and I named him after the Mulan's dog in Mulan, since that was my favorite movie at the time. He was a huge part of my life, and whenever I would go to my mom's house, the first thing I'd look for was LB. Usually, he'd be in my actual brother's room, and he'd meow when I'd say "Hi Brother". And also when I walked in the room. Me and him would always cuddle, and take selfies. He was seriously the best cat ever. The last time I saw him was when he was on oxygen at the vet--I said my goodbyes to him, sobbing, before he passed. I held him post-mortem, and all I wanted was to bring him back. I begged and cried into his fur, "Please, Little Brother, come back".  I think my sister, age 8, took it the hardest. Her and LB were best friends. They would sleep next to each other every night, and she had never known life without him. At the vet, I saw my little sister getting out of my stepdad's car, and even from a distance, I noticed that her face was bright red from crying. I'm never going to forget him. I will always love him. Anyways, just wanting support and to vent.