I made a HUGE mistake and I don't know what to do...?

Soo yesterday me and my friend made plans for today because today is Canada day. We went out to a bridge where there was tons of people having a party and jumping off the bridge into the water and stuff, so I wore my bathing suit. I self harm and I wasn't thinking and I took off my shirt and then I remembered, that I have scars and cuts all up my arms and on my upper arm it says 'stupid' and when i realized i folded my arms, but everyone could still see it. Also there was scars on my belly. A guy asked me if I got raped by a cat, but I said it was from my dog, which he obviously knew it wasn't because he could see the 'stupid' and then a girl saw it and she asked me what it was then i quickly said it was from my dog, and then she saw the 'stupid' and she was like wtf.. ? and Then I showed her my arm and said that my dad did it to me and she was like "hahah what.. did he like beat ya" and I was like idk. And then she's just like oh well it looks like you're emo and you hate yourself. And I just tried to ignore everyone the whole day. And there was like 70 people there, and I never talked to anyone because they would ask what's on my arm, and my friend ditched me for everyone that was getting high and smoking and stuff, and no one knew who I was and It was just a horrible day and I'm going to have to see some of them on monday because I have to go to summer school and they are guys, and they are jerks so more than likely they are going to say something. It was just a horrible mistake going today and I have no idea what to do.... Oh and btw, don't get mad at me for saying that my dad is the one that did the stuff to my arm, but I don't give a f-ck if people think my dad is a jerk because he is. He is the reason for my cutting and so it's not that big of a deal that I blamed it on him.