I feel that I was happy when my best friend got rejected
How could you? She got rejected by her crush?
Yes, I hoped that she would be single so that I can have her for myself.
You shouldn't find joy in things like that. You should support your friend and have her back, not strike while she's vulnerable.
She deserves this. I don't like to see people happy and she is a way too happy of a person.
But isn't she your best friend, why would you want to feel this way? How is she going to feel when she finds out you don't want her happy?