Why can't I be happy for my best friend?

When I found out I was pregnant I immediately told my best friend. I received the second best news that day, so was she! She found out a week before I did. It was her second, my first and I was so excited we were going to go through this together. Not long after I started having bleeding. A month later I was told I had a miscarriage and had to have a d&c. I had kinda stopped telling her what was going on, as I didn't want to freak her out and I was heart broken to have to tell her we lost the pregnancy. When she found out it was a girl I cried, not out of happiness but sadness. I should be finding out what mine was that week too. Well today she gave birth to a healthy baby girl and all I can think is I should be too. I can't even feel slightly happy for her. I just want to curl up in bed and cry. Will I ever be able to look at my best friends daughter and feel happiness? I should be happy for her, I should be making plans to get out her way and see her and the baby and be so happy. But all I want to do is hide in bed and cry. And I feel like a crappy friend even though I am sure she understands.