There is the person that I'm going to confront aggressively in front of their best friend.
Do you have a goal in this confrontation?
I want the person to know that I'm not weak. I want her to fear me as much as I fear her
You may have a good reason for confront the person. However, aggressively confronting the person out of the blue will make it appear that you are unable to control your emotions. Instead, you should stick up for yourself only if the need arises. In the meantime, actively avoid the person and keep your distance.
I just want to show her what I'm made of.
Lashing out aggressively won't accomplish anything when it comes to this person and simply avoiding them is a more productive way of solving this issue. Showing her what you're made of will only make them respond in a way that is even more aggressive.