RY – the vast majority of kids who go to Frum schools stay Frum. Kids who go to public school usually don’t, or at least became less Frum. Of course, there can be exceptions depending on both the kid and the school, but that is the exception, not the rule.
It sounds like your school was not the right place for you (or maybe it wasn’t a good school in general), but that doesn’t mean that you should have gone to public school – it probably means that you should have gone to a different Frum school.
Too bad you didn’t go to my school – not only can I not think of any Frum kids from my school who stopped being Frum, a very large percentage of the not-Frum kids became Frum.
My sympathies for your bad experiences 🙁
I hope you can find a way to undo any damage done and find an environment/community that you don’t need to be sheltered from. They do exist.