Stephanie. (((((HUGS))))))
Your heart is broken and of COURSE you miss your boys. Although I guess you made this decision to provide the best situation for your boys, it doesn't mean it wasn't the toughest thing you will do and it doesn't mean it was easy or pain free. For you, it is a profound loss that you will need time and support to properly grieve.
You said it has only been a month since you placed them into their adoptive home. So, I'd tell you to keep seeing the therapist and keep open communications with your friends who are supportive. It will take time so stick with the therapy.
Unless there was severe neglect or abuse, I don't understand why you can't see your boys, or at least have a semi-open adoption? Can you write letters to the boys to help with your feelings? Even if you can't send them, the act of putting things down in letters to them, or a journal may help you work thru this difficult time.
I am so sorry for your loss. Please stick around so we can offer support to help you thru this time.