If you knew it was wrong, you shouldn't have posted it in the first place? Or did you not notice the change to the rule until it was too late? I know the edit to the rule's a bit recent.
When mods re-post rules, re-read them. Sometimes rules don't change, but sometimes, they do. You would've noticed that rule, and you wouldn't have an infraction right now, would you?
Also, infraction = not the end of the world. You're overreacting. You're not the first with an infraction, and you're not the last. It'll eventually expire, and all will be well again, especially if you learn from your mistake and not break the rules. :D