First of all, congrats on sticking to an exercise plan!

It seems like you generally have a handle on meals and exercise, which is great. Those are great life changes.
Onto the binge topic, this was a slip, but don't let it get you down forever. Take it as a bump in the road, and move onto preventing the next binge. It seems that you have difficulty with portion size, which is something I struggle with as well. It makes it so that I can't keep anything in my dorm that has the potential to set off the trail of food. Which means absolutely no chips or candy, because when I have one, I will have another. I don't know your living situation, but keep lots of fruit and vegetables handy. When you need something sweet to chew on, go for an apple.
And try not to get too focused on the scale. Many people get tied to that number, and it really fluctuates due to time of month, water retention due to muscle building, and who knows what else. This is a lifestyle choice, so it's good to get comfortable with it now and focus on other milestones too, like inches lost, miles you are able to run, or weights you are able to lift. ** Like the person above, who has a mile ticker in her signature.
Don't get disheartened! Keep up your good habits, beat back your bad, and know that it might take a while, but it's worth it.