I lashed out big time

I am known to be a very chill person.

Like I'm not just saying that to say that but I think the only time I raised my voice was to my gym teacher last year who was yelling at me (a very quiet and participating freshman) for forgetting to bring tennis sneakers for my first time even though we can use borrows 3 times per year.

But today I was practicing tennis with my friends and my best friend kept jokingly throwing the balls at me and it hurt so bad and I kept telling her not to. I think the fact that I tried throwing them at her and missing made me even more upset. She kept joking to my friends about how I was just acting emo (shutting them out with music and frowning) because I wanted her to feel bad.

So while we were walking home she kept saying I was overreacting and ignoring her was crazy and I got really irritated and began walking across the street (a very busy road with like 5 lanes to keep attention to) and next thing I know my 2 friends were jerking to pull me in because immediately after 4 cars zoomed through the lane. They all thought I was crazy or wanted to die but I didn't even realize it.

I'm not on my period or anything (they probably think I am) I'm normally on schedule so it should come in about 10 days. Why did I freak out so much it's really not like me and I think I scared them especially since right after I almost got hit I yelled at her to stfu in public where ppl were around staring...