School weight-gain terror!

Hey, I'm starting summer term tomorrow and I am completely terrified about my weight! I started going to community college in the summer of 2009. It was an easy load at first because I wanted to take it slow having not been to school in over 20 years. I was also determined to lose weight and I joined the local Biggest Loser. I was eating better, but boring, repetitive food, and was exercising every day. I did wonderful in school and won 2 of the Biggest Loser sessions. Then I added more classes and my son started going through something awful (I'm a single parent to 2 teenage boys). I began to stop focusing on my own health and started focusing on my son's instead, and school of course. It was really tough for a while. I gained 10 lbs over a few months and was not exercising at all anymore. I still managed to keep my 4.0 and I applied for scholarships, but wasn't thinking that I would actually get one. By the end of the school year in 2010, I had won 6 scholarships. One of them was the largest one you could be awarded in the state. I was told to stop thinking so small and to really go for it at school, all because of that huge scholarship. I thought I would go ahead and apply to my "dream" college.... it was already time for them to close down applications because school started in 3 weeks. I applied and was accepted 2 days later. I was excited, but scared. I had to go to school full-time and keep my grades high in order to keep the scholarship. I started school and started snacking on the school's deli cookies and muffins and candies. I didn't even notice I had been eating almost none stop. It didn't help that I was dating someone who loved big girls and I had no idea he felt that way. I rarely had time to breath, let alone exercise, or so I told myself. I was terrified of losing my scholarship. So I ate more and more. I gained 70 lbs. during my freshman year! Seriously!
This story could go on forever... and probably already has some people falling asleep! LOL so I will get to the problem.
I finished my freshman year at the university about 1 1/2 months ago. Since then, I have joined a new Biggest Loser. I was hoping that by doing that, my state of mind would go back to the healthy mode that it was in during summer of 2009. It didn't work at first, but I'm getting there now. I've lost a little weight and exercise every day unless something major comes up.
BUT I start summer classes at the community college TOMORROW! I have to get these classes done before I head back to the university at the end of Aug. I don't know how I will react. I know the class I am taking that scares me the most might have me munching and bingeing and too busy studying to workout. (I literally study for hours on end) This particular class is a 4week, 4 days a week, over 4 hours a day, accelerated Biology class with lab work. I couldn't handle biology when I tried to take it before, so I dropped it until this summer.
I know people will say, "just take some carrot sticks, and water, and fruit, etc..." but when I get freaked out, I stop exercising and slowly start eating the most convenient thing I can get my hands on. I don't think I have enough of an imagination to avoid falling into the boring gap I fell into before. I was eating the same old things, over and over, and that's part of why it was so easy to give into other food that was bad for me. I also will not be able to use the school gym because I will be rushing home right after school is out.
So, that's my fear right now.... I don't want to go backwards. I've been all gong-ho about getting healthy and in shape. It just seems like I'm faltering today because I realize I will be going to school tomorrow.
If anyone has any suggestions, I'd like to hear them.