She knew after the fact that I had caught her (not during) and we appropriately spent the rest of our brief teenage years carefully avoiding one another. I heard gossip and what have you through the high school grapevine - my guy friends pretty much patted me on the back, usually stating some variation of "She is what she is."
It turned me off to casual sex for years and years, but taught me a valuable lesson on how you perceive women versus who they really are. It's really easy to not notice flaws when you're wearing rose-tinted glasses. That mistake caught up with me again later in life, but it was easier to accept the next time.
Also, I now hate lacrosse.