We know Peter wept after the 3rd time he denied Christ. You do not weep unless you realize you've done wrong. Why wouldn't we believe each time Peter sinned and realized it, he realized it was a sin against Christ? Peter set that precedent long before his vision and Rebuke at Antioch.Peter was wrong about other things, so if he did seek forgiveness, it was wrong. BUT, you are assuming he did. You cant build your theology on something like that.
Your sin is already forgiven is it not?
But if you want to sin and think it's cool, you have seemingly found your loophole. Go and be the best sinner under the guise as saved that you can be