Iam very sorry for your loss. I know what it's like to lose a best friend, and companion. I cry like a baby when one of mine passes on. Again my condolences and sympathies for your loss.
It cannot be denied how close one can become with their dog. Especially one that is inside and even worse when it is a Chihuahua. Something about those dogs. We have always had an inside Chihuahua since we were first married. The last one had to be put to sleep on our 31st anniversary. Wife stated that she was done with them after that because of the pain. (another reason parents need to pass before their kids if loosing a pet is that hard) But time heals most things and it is just a matter of her finding the right one and that will be that.
Our pets, are family, however sometimes they are better in some ways, always listen to you, and never say you should have done this or that. They keep our secrets, secret. They always show their appreciation when we talk or just share a snack with them when watching TV.
May you always have the fond memories of the humor she brought into your life...