I'm going to dump food on my girlfriend's plate at a wedding until it overflows.
Is there a reason you want to embarrass her like that?
She is my biggest enemy and I don't like her anymore.
That is a mean thing for you to do even if you don't like her. It's bad to waste food especially at a wedding where it cost a lot to have food there. You should make this a happy time and talk to her about your feelings after.
You don't understand my pain.
Pain or not, wasting food is wrong and it will accomplish nothing. Perhaps you could maturely and respectfully break up with her before the wedding that way you will avoid the situation completely.