I am so sorry about the painful emotions you are feeling and that you are grieving so much.
I hope you can find a way to feeling at peace about how Littles found his family, and can soon move on to your next chapter.
I know this experience has given you some gifts, but you need to grieve now, and get some perspective later.
There is no way someone could go through something this deeply challenging and not feel how you are feeling. Just be gentle with yourself, and let yourself say your sad goodbyes. I am so thrilled that a family will adopt Littles, and I hope that that will be the main feeling that remains with you as you move forward in life.
(By the way, I hope you don't mind my giving you my pastor's view of God, and that is that God does not send people bad things. I hope you let go of that worry.)