Failing

Does anybody else feel like they are failing? I feel this way all the time. Especially today. The guy that I wrote about in my past journal entry, him and his wife had their baby today, and everyone is running around the building showing each other the pictures he sent.
And all I feel is sadness and jealousy...and a bit of anger. Angry that I didn't get to experience all the joy and happiness that they are enjoying probably right at this very moment.  All last week, all I heard him say was "As soon as this brat pops out we get to claim her on our taxes." Really? Who says that? I wanted to get up out of my chair and kick him...and then I start to think, is God testing me? And with my feelings of jealousy and resentment am I am failing him?
I have prayed and prayed and prayed month after month after month for God to send me another baby, but 1.5 years later I have failed at this also. 
Is He waiting for me to get over this resentment I have for everyone else in the world who gets to have a baby before he answers my prayers, or is Motherhood just not an option for me?