I think in the long run it will be better for your dog too. I have a child so I know the connection to a child but I also have a dog and a cat and I love my animals dearly. In fact they were often a source of conflict between me and my stbx because he always felt they had no place in the house. My vet has indicated o me that dogs essentially have a memory of about 3 months so after that your dog won't feel any loss from disconnecting from your stbx. Yes your stbx will still have the loss but then he obviously didn't consider the consequenses of betraying you before he did it and this is YOUR dog, a possession from before the marriage so don't worry about his pain, he didn't worry about yours.

Christine