You have my deepIest condolences, I'm so sorry about your wife and your little yorkie....
ps....having been there I know just what you're saying about dogs grieving, my cocker Tessa was totally lost when I lost my husband and it's like a double whammy....you've lost someone you love and you're grieving horribly and then to see them also suffering it makes it even harder
I really am sorry about your losses and all the best to you with your new little yorkie. I hope she helps you smile and there is nothing like a new puppy to do just that.
also - what a good thing your wife and you did adopting a 13 year old. That's pretty special.