Should I be mad or am I overreacting?

It sounds like your friend was trying to protect your feelings. She knows how long you've liked this guy so to find out he likes her would put her in a difficult situation. I would try to see it from her point of view as she really hasn't done anything wrong. It's easy to say that you have an honesty policy in theory but sometimes life isn't so black and white. She sounds like a good friend.