Forgive and forget?

But how will people ever become aware of their mistakes if you ignore their wrong-doings?

Maybe the mistake is only a mistake in your eyes. Maybe it's just a difference of opinions. Maybe you shouldn't have become upset at them in the first place. Regardless of the above, what they did was wrong/hurtful in your opinion. So you have the right to be mad at them and voice your opinion. Often times, this mistake leaves a mark forever that will slowly fade, but it will never fade away.