Awww, honey, don't be so hard on yourself! You seem like such a good person, so there is no need to feel so bad or be afraid to post! This site is all about support and advice... We're not here to judge you (although there is plenty of that, but you know how we women can be, hehehe)
But as to your dilemma... I would speak again with your breeder and let her know that it's not so much for the HEALTH of the puppy that you would like for him to stay a little longer... but for the socialization skills that he learns from the mama pup and his littermates. Sure, as far as the health goes, it def can't hurt to stay a little longer, but as long as he is weened and big enough, that's not really the issue with going home too early. It's more to learn things like bite inhibition and other vital socilization skills.
I brought my youngest home at 6 weeks (got her from a shelter, so it couldn't be helped) so I know first hand how difficult it can be to properly socialize one of these young ones. It is alot more work! That's not to say it can't be done... just that it's unnecessary!
So, I would just speak to your breeder again, and if she is still unwiling to work with you... I would have to say that you are making the right decision in leaving this pup behind. I know that it has to be an extremely difficult decision to make. It's so hard once you've fallen in love with one, AND you've already laid down the deposit... But look at it this way: losing the deposit, however much money it may be, is worth it to eventually buy the best possible breeder you can. Yes, I said buy the best BREEDER, because she's the one crafting this wonderful little companion you'll have with you for years and years to come. And if she is unwilling to listen and learn now... just think of how many corners she may have cut in her breeding program that you DON'T know about! Being a good breeder is more than just having two healthy dogs and throwing them together. Does she do genetic testing? She says she shows... does she have proof of this???
Think about it this way: Many people say that having a yorkie is like having a small child, and I agree. You take these babies into your heart just the way you would a child. Now if you had any doubts about the person you'd choosen to "engineer" your baby, (aka your husband!) would you go through with it? I know I wouldn't! You don't make babies with a guy just because he's cute and you happened to spend alot of money on his Christmas present, and you don't buy a yorkie from a breeder who is throwing up red flags just because the pups are adorable and you put down a deposit!
*Steps off soapbox*
But seriously, I think you know what you need to do, and you seem like such a sweet person. So whatever you decide, please don't leave the community. We need people on here who have big hearts and the desire to do what's right
Best of luck to you!