You're not a terrible person - you're a normal, human one with instinctive responses. Just don't ever let the friend know of the jealousy - in any case, it's far more about your own sadness at what might have been than actual jealousy of her, I'm sure. If you can't speak to her yet, email/text.
It doesn't make you a horrible person, it makes you human. I felt the same when I was trying for no2. It took us 15 years and in that time my sister had 4 children and my cousins had several between them. I couldn't help feeling jealous-and ready to kill when my sister would moan about her 4 with the words 'at least you only have one'.
Sometimes you have to try and swallow your feelings. Your happiness for your friend will come, it may just take a little time.
YANBU to feel the way you do; we can't control our emotions. You can make yourself offer congratulations though, even if it hurts inside.
I know how you feel, because the same thing happens to me. It's rare that I feel a genuine happiness when I hear someone's baby news. Usually it's a horrible kind of jealousy, which I think is still a result of the fact that I had IVF to conceive and had to watch everyone around me have babies when we were struggling to get pg. That feeling never quite went away, even though I now have my family. I have to be firm with myself and not dwell on these feelings.
Whilst I can understand why you might feel sorry for yourself in the circumstances that shouldn't prevent you congratulating someone else. If you have problems, do something constructive to resolve them. Begrudging someone else a bit of happiness does you no favours.
Feelings will come and go- difficult to control these. However you can control what you choose to do. Go out of your way to congratulate and support her through the pregnancy and after the birth. You will feel better- honest!