I'm sorry for your loss. Here is one idea - set yourself a period for mourning. Many cultures have a tradition of some set period during which people follow rituals of mourning. (Jews sit shiva, for example; Roman Catholics may gather as a group of friends to say the rosary each day.) How long would you like to modify your behavior in recognition of your loss? 10 days? 2 weeks? a month? Give yourself permission to let your behavior during that period be modified to allow for your grief. Maybe decide on one daily treat that you don't normally eat but that is small enough that eating it once a day for this length of time isn't going to destroy the healthy progress you have made. Maybe create a simple ritual like, when the children are in bed, stepping outside with a cup of tea and looking at the stars and being thankful for the companionship of your late dog and allowing the tears to come. Decide on a ritual end to the mourning period - when you are going to return to normal life. (Not that you won't continue to feel grief at times, but the first sharp pain will have passed.) What will you do to mark that? Maybe go to a park that you loved to go to with your dog, and find something that speaks to you? Maybe bury the dog's collar in a special place in your yard? Decide on something that would be meaningful to you. (Maybe involve the whole family in this - your children are probably hurting too, and giving them permission to talk about grief and loss is a good thing to do.) Decide that when your mourning period is over you will return to the eating habits that you know are healthy for you.

Missing your animal is not stupid at all. Dogs are like family, but you need to take care of yourself. Maybe some short walks during the day would help your mind and body?

Oh. This was for a dog. I guess I can understand. I'm sorry for your loss, I'd bet it is just as bad as me losing my grandfather, since you loved it, I loved him. I'm sorry.

But I'm totally understanding grieving and eating (because of my grandfather)...

Missing and grieving for your pet is not stupid. They are part of your family. *hugs* to you.
I am struggling with the same thing myself, my 13.5 year old golden retriever passed away in his sleep on Friday night, we knew we wouldn't have many years left but didn't expect it to be so soon, he was still eating and acting normally and he recently had his checkup with the Vet and was given a clean bill of health apart from arthritis.... I don't think it's something you can be prepared for and it hurts.
I try to keep myself busy.....read books, surf the Internet, housework, even naps on the weekend to avoid eating. The first few days after I ate at what would be maintenance....I wasn't losing but not putting on either.
I have another close friend and she is also going through the loss of her 16 year old dog, she puts time aside to light a candle near a picture and "meditate".
I know this is a rambling post, but I guess I am trying to say is be kind to yourself and let yourself grieve and do things to keep yourself busy instead of trying to fill the emotional hole with food. (hard I know....). .