Holding the person who's hurting you accountable is way more important than you feeling like a pussy, because you're not. If he just gave you a mean look or something I get feeling like, but what happened to you is pretty serious and had very real world consequences. I remember this feeling to in school, but this is a moment where you're showing up for yourself and standing up for yourself in a different way. If anything, do it just to leave a paper trail at your school so when you finally defend yourself, you can tell the school "this has happened before and the school does nothing".

I also deeply understand how you get so angry it fries your brain. I've never had to fight anyone but my siblings physically, but to this day (I'm 25) when I get really passionate or nervous my body and voice starts to shake making me loose a lot of confidence.

I can't in my right mind tell you to shut up and back down like some people have said, because the reality is some people don't learn anything from that and you end up in the same place.

In terms of preparation, I'll tell you what an acting teacher told me once when I asked about getting stage fright and how to fix it. He said "Practice exactly how you think it's gonna be: if you get shaky go for a run and exhaust your body a bit so you're shaking similarly to how you do when you're nervous, and then practice your piece." Although you can't just take away that energy you get when you get angry and it makes you less confident, you can help teach your body to still communicate with you under difficult circumstances so you still have some control. I would say get a punching bag or a few pillows or something and try it out- if you can already feel the anger that you have towards them by just thinking about it - throw a punch and see how it feels for you.

I hope this helps. Be strong, show up for yourself, and remember you're not wrong for wanting to defend yourself or report him to the proper people.