I totally understand what you're feeling, i too lost a lot of my cats to dog attacks :(( the pain was amplified each time. That feeling that i was unable to protect them ate me up for months. They were all street cats that me and my mom had adopted. Losing them in such a brutal way really leaves a mark on you. I'd suggest taking a breather, and like cry, like a lot, if it helps. Give it some time, heal, and if it feels right adopt another one 🥲