(17f) AIO after seeing someone die yesterday?

Hello, I'm a 17-year-old student and live in a not-that-good part of Germany. Train stations are full and there are a lot of crackheads.

Since I'm about to write a math exam next tuesday, my teachers offered afterschool help. Initially I wasn't planning on going, but I still decided to go. After 2 hours I walked out of the school to the train station. My younger sister wanted to come visit me and go home together. I waited for her, sitting in front of the underground track.

I heard the sound of the train coming. I looked in the direction of it. There was a group of people a little older than me standing there. Soon the train was visible. It was just coming out when I just saw a guy in complete gray clothing fall/jump right in front of the train. It made a hard splashing sound. Everyone went silent, and my head was spinning, wondering if what I just saw was real or not. I looked at the 2 train conductors; I looked at the group of young people. I listened to an elderly lady calling someone after a few seconds, explaining what just happened in a shivery voice. She was sitting with her back to what just happened, so I think she only heard the short gasps and splashing sound. I called my sister hoping she wasn't in the train that just hit the guy. She was in it, asking me what happened and telling me that they felt the train shake and then the lights turned off. The doors still closed. I walked toward the train to look to see whether my sister was in the front or still in the part of the train that's in the tunnel. I could gladly see her. The body wasn't visible, but I heard the group of people yelling, "There's blood!".

I've been feeling very weird. Time is passing very quickly, and it feels like my body is shivering while I feel nothing and then suddenly feel a lot when the event pops into my mind. I feel like I'm overreacting because whenever I tell someone, I start violently shivering, and my voice starts shaking, but it's weird since I can't control it. My mother experienced something like that too when she was younger, so she didnt really care when my sister told (I knew it wouldnt make a difference so I just came home and into my room as always) her what happened and asked me wether im okay following that by "youre ok.". I already have a shit relationship with her, so this really solidified my hatred and disgust toward her.

I went to school today. After arriving at the station I looked at where the guy jumped/fell. There were socks. I continued walking to school. After realizing that focusing wasn't an option today, I went to one of the guidance counselors, and she allowed me to go home for the day. Since then, 2 other teachers texted me.

The reason why I feel like I'm overreacting is because whenever I told people of what happened, they kind of brushed it off, but some asked whether I was okay or not, which I don't have an answer to. The guidance counselor did have a reaction, though.

I'm already in therapy because of diagnosed moderate depressive episode, social anxiety and body dysmorphia. I feel like yesterday was my 13th reason. He most likely killed himself. He didn't make a noise or yell. Maybe he just didn't have the time to react since he fell at the perfect time. He died during Ramadan. I'm glad there weren't any little kids from the elementary school since it was 5pm. I'm glad my sister didn't see anything. Haven't read anything on the news/police post yet, but I'll make an update as soon as I do