Thank so much to everyone who responded. In retrospect, it wasn't a very well thought out post, and it was more of a reaction to needing to share that such an odd thing had happened, but I hadn't reflected on it much (duh.)
Upon reflection I want to say this:
I believe strongly that every child deserves to be welcomed wholeheartedly into their family. Whether that is biological/genetic/surrogate, which ever, the key to me is being welcoming. In the process of going through infertility I have had to work up to welcoming each potential child (IUI, IVF, DE, DS, DE/DS [still working on those last two]), and their origins, and the realities that their origins would impose upon them. This has been both painful and growth producing, and yet grief has been with us every step of the way. And yet, when we have grieved and prepared a place in our hearts and minds for each of these potential babies, we have felt joyful at the prospect of them.
When I got the call yesterday, I had the sense that I was not prepared for this child. I hadn't prepared a place in my heart and mind for this child, and that was the bottom line. If we were in the process of preparing for adoption, and this opportunity had come up, I think we would have jumped at it. Who wouldn't want a sweet baby boy? I certainly do.
There are families all around, and even people my friend knows who have been preparing a place for a child through adoption, and to my mind, that is where this child will be welcomed. If we had said yes, it would have been with trepidation, and misgivings, and without really knowing if we were ready to welcome him.
Attachment is so complex, I won't try to parse it all out here, but as I said a few posts ago, there is no baby without a mother, and I was not prepared to be his mother. He was not my baby in my mind. He deserves that--a mother ready to imagine him, to know him, and to love him with all her heart and mind.

