I know how you feel. I haven't got Deegan neutered yet because he's only 12wks, but I've been thinking alot about it lately. I am nervous too. But I just keep reassuring mysel that lots of other yorkies get it done and they all come out fine. So I am positive that the surgery will go well.
When he comes home, just be sure to give him lots of love

and try to keep him as comfortable as possible.
Good luck and keep us posted, I would like to know what to expect afterwards.