My best friend had a miscarriage and it made me happy.
That's horrible! What about that makes you happy?
She was an emotional wreck when she saw the blood. I'm glad it wasn't a successful pregnancy.
It's terrible to be happy about someone else's misfortunes. You should be comforting your friend instead.
She will get over it and she has many other kids.
It breaks my heart that you feel so callously towards the suffering that your friend just experienced. Whether you wanted her to have another kid or not doesn't matter, you shouldn't find joy in her loss.