Teacup yorkies usually have severe brain damage. They have been bred past the point of functionality. Many of them have seizures, and at the very least they shake all the time. They are untrainable, incapable of forming anything approaching a bond with you, and not even very cute compared to other breeds. I have a coworker who has one and she says it is incontinent every time it gets excited.
From the standpoint of a pet, it is basically a large rat that makes more noise, costs more to keep, and has larger poop.
I'd say, "Honey, I love you, and I know you thought this would be a nice surprise, but this just won't work for me. Let's put up an ad and sell him for a small fee, and there will be a nice family to take him that will actually appreciate him. Then we can look for a dog that we can both love."