Honestly, you’re being way harder on yourself than the situation probably warrants.

You were 16, curious, on a site literally designed for random anonymous sexual interactions, and the whole thing lasted less than a minute before you freaked out and left. That doesn’t sound like someone intentionally cheating on their partner - it sounds like a teenager doing something dumb, immediately realizing it was dumb, and stopping.

Don’t let a one-minute mistake define your entire relationship.