Dear Mackir, I am so sorry for your loss, and the dreadful shock it must have been.
I too say that three months is not long. I lost my husband two years ago three months after he had been diagnosed with cancer. We at least had time to say the most important things to each other, but that didn't really help.
I am so glad you have the dog to feed, walk and cuddle- I have two cats and cried all over them for weeks. But like your dog, they needed to be fed, played with, and consoled for they were missing their master.
As to eating, perhaps you can do as I did. I ate whatever I wanted, whenever I wanted it. No fussing around with what was healthy or fattening. After all not eating is definitely not healthy and I felt made me less able to cope. And no attempting to eat the right meal at the right time, either.
The cats thought it a little odd that I got up at three in the morning to make something or other that I had wakened up fancying or had dreamed of. Their expressions quite plainly said that no sensible person eats toasted cheese, or baked beans and fried eggs at that time of day!
And the same too dear pets knew I was daft when I scrubbed the kitchen floor in the middle of the night - but I could not sleep - the empty half of the bed was making itself horribly obvious! And the kitchen floor was dirty!
Sometimes cleaning helps, other times you just have to sit and weep. Do try to eat - perhaps something you like, but haven't had for years because your husband did not care for it? I worked my way through a short list of things he would never eat, and it has taken me the better part of the two years that have passed to want to eat soup again, as latterly that was all he could eat. (And I used to love soup).
And keep in touch with us - I received such a lot of help and support on the bereavement thread, either openly or in private messages. PM me if you want.
There is no right or wrong way to grieve, only your way of doing it, as we are all different, and our marriages cannot be compared either, but the feeling of being lost, and of the loss are perhaps more alike.