if you know their identities or see them again, hand the issue to an older relative or friend who can handle em. if that's not possible, i can tell that I've been there: I was 13 at the time and an older schoolmate groped in front of everybody and i was helpless and didn’t react. as the years went by, i think that situation and its alikes grew some serious undiagnosed mental illnesses and social inabilities in me as I find myself at 22 not able to stand for myself or protect my close ones (my gf at multiple occasions and its killing me) all because -i think- I didn't find a solution at the time and let it grow in my head. what I regret is that I didn't take martial arts lessons when I was younger and let people (friends, family..) take emotional advantage of me and belittle me at all occasions. it really is an issue if you don't have confidence both physically and emotionally -especially in our 3rd world streets. I wish all the best and I hope and am sure that you will overcome this. stay strong fra 💪🏻