I agree with luckymommy: A little over a month ago I fell off the wagon for a week, just like you. Regained some of the weight I had worked for 5 weeks to take off. Just like you. Felt pretty sh***y about it, again, just like you.
But I picked myself up by my bootstraps, dusted myself off, and continued on. It took two weeks, but I lost the weight I had regained, and have continued to drop more.
Yeah, I could have sat around and wallowed in my feelings. But that's how I got into this mess in the first place: it's easier to sit around and stuff my feelings down with food and berate myself for it than it is to do something about it. It wasn't super easy to get back on track, but the alternative is no longer acceptable to me.
So, even though you don't feel like it, just try to put yourself on auto-pilot and get going. You
can lose what you regained, and you
can keep going. Don't think about it: just do it.
Most of us have had similiar experiences with getting derailed, but you gotta just put the train back on the tracks and keep going!
