I am so sorry for your loss. Please continue to cry and share your thoughts with us. We will help you heal. Thank you for posting your story, you may not know it now, but you just saved at least one Yorkie life by making people aware of what happened to you and what could happen to anyone of us.
I don't know how long the pain will last, but try to remember that Zack will always love you and he will always be will you until the day that you two meet again. He and his love for you will be waiting for you until that day comes. But in the meantime, he doesn't want you to be sad. Try to remember the good times and then turn that into the excitement you will have when you get to spend eternity together.
I haven't lost a pet (yet) but I did lose someone so very close to me. The hurt still remains with me, but I know when my day comes, he will be there to greet me, and that makes me smile.