Hi fireballgirl,
Besides having a plan A (and a plan B for unexpected events), and the ladies before me have said it well, I would suggest some soul-searching and getting as emotionally and mentally prepared as you can be for the road ahead. Think about why this change in your life is important, what your goals (both short-term and long-term) are, why you sabotage your efforts (why do you eat the way you do, what are the early signs that preceede mindless eating, how you're going to deal with those situations), etc. I find that if I am able to see the pit ahead of me, I won't fall into it, so to speak. Also, try not to dwell on "hopping off" (I am from Europe, so I know what you mean

, just evaluate why it happened, try to figure out when you'd seen it coming, learn from it, and hop back on. The reality is, hopping on and off happens. The thing is though, to try to stay on and enjoy the ride as much and as long as you can.
You're not alone. Good luck!