Worst case scenario:
She told her folks everything and Your dumped

- I doubt that will be the case though.
2nd Worse Scenario:
She's told her folks everything BUT still wants to continue dating.
This would stink, but to be fair, youve orchestrated this yourself and personally would put it down to experience and forget about it. How many blokes out there do you think "put up" with their in-laws for the sake of their partners?
Show the parents what a true man you are and say sorry to their face and offer to take them all out for a meal. Extra brownie points maybe?
YES, it is sucking up, but your doing this for your g/f, winning her folks around will make things a LOT easier else they will be constantly nagging in her ear that your no good for her and to get rid.
To be honest, if a b/f of my daughter came into MY house and slated my Mrs, I dont think my daughter would ever see him again.
Best Scenario: She forgives you and has NOT told her folks.
Your a lucky SOB and need to be on best behaviour for a LONG time.
I think that deep down, you know you had a retard moment but now have to face the music. You will have worse to come so just suck it up. I hope everything works out for you.
Keep us posted.