Leave the horse alone while eating to begin with. While there are times you may need to mess with horse at meal time, usually there is not any reason to.
And getting horse to behave shouldn't take any longer than couple of minutes either. No reason at all for it to take an hour or more at all. Ever.
Lesson can be taught in few minutes, no more than 5 if you are dealing with more than one at feeding time.
Take lash whip, move horse off of you, keep them off, dump feed, keep them away from you, and lesson learned. Back off feed but make them stay back, until you decide they can come up.
Dragging it out is senseless and waste of time.
Also, check you handling skills, if you are a constant talker, quit it, don't "soothe" or baby horse and act like you are the one in charge.
And if you have to correct horse, don't jabber, or let horse back in or do the "I'm sorry I got mad at you" routine.
You have more than likely been displaying submissive behaviors and horse has now gotten settled enough to put you in your place, according to his idea of just where that is.
Horses make me a better person.