I'm sorry to hear about Violette and I understand how bad you feel. My 3 dogs killed Clarry Cluck 2 and a half weeks after I brought her home. I hadn't latched the gate properly and the dogs got into the main garden where the chooks were ranging.
As if that wasn't bad enough, I forgot to latch it again a few weeks later and Teddy Jack Russell caught hold of Myrtle, dropped her when I grabbed him, got away from me and caught Myrtle again. I rammed my hand into his mouth so he had to drop her. I was lucky this time, she wasn't hurt.
I had always hoped the dogs would be 'big brothers' to the hens. It was obvious from Day 1 that this was not going to happen