@glitterbag,
Yes, everyone makes mistakes, but part of growing up is owning them. ESPECIALLY when the mistake is known by many.
I actually have a similar story to OP only i was 17 and in high school dating my would be future cheating husband and i fooled around with a friend. I owned my behavior, I never had sex, but it got close and would have been had we not been interrupted. My husband and i were not exclusive at the time (We did not have that talk), only been dating a month maybe...but still. I confessed. It worked out fine in the end, Why? Because people DO make mistakes. Is how you handle the mistakes in the aftermath that define who you are as a person. Are you innately deceitful? And dishonest? If the answer is no, and that is not the person you want to be then to remain true to yourself you should confess.
Glitterbag, I get the feeling from you that you hate social norms and rebel...maybe naturally deceitful. But you are entitled to your opinion.... I personally would never feel safe with you as a partner, but to each their own. Good day.