You just go ahead and cry, girlfriend. I know just how you feel. I have cried every single time i let a puppy go to it's forever home. But....
I have been so blessed with great buyers. I still stay in touch with them and they send pics as they grow up. (Some as far away as PA and TN) I told the buyers that they were just going to have to consider me 'grandma'. They just laughed and promised they'd stay in touch. And it is WONDERFUL seeing my babies with their new families and seeing how happy they are. Just remember... you were one of those new forever families to your little furbabies.
The crying is heart-breaking, but it only last a little while. Usually just till that first time you talk to them after they get the baby and then after you get the first set of pics!
So hang in there, girl!!! (And yes, it will hurt terribly, you will cry, but you will eventually smile!)
