I am so sorry to hear about Brio. That must have been just devastating to find her like that. I'm so very sorry.
I think I would wait on a new dog. Your and Murdy both need to go through a bit of a grieving process. A new dog would just add to the confusion for Murdy, in my opinion. Take some time to comfort each other and go through grieving for Brio. You know another dog isn't going to replace her (I'm not telling you another you don't already know ) but I think it would be lovely to get another dog once you have both healed and are truly ready for another companion.