What do you do if your best friend spills your biggest secret?

I would get angry. That would be my first reaction, maybe I would no longer talk to her but I think we could still work things out. I would ask her, why she did it and would also give her time to explain and to apologize. After all she is still my BESTFRIEND and I if felt that she feel sorry for what she had done I would forgive her.

But it's all up to you. This is just a friendly advise since I have experienced it too.