I feel your struggle. I get mad at myself when I feel like I slacked off, even for a day. The best thing that I realized that I could do was to just step it up a notch the next day. You can't change what you did in the past. Don't beat yourself up over it. Just step it up tomorrow and take it one day at a time. I use two notebooks. One to record my eating habits, another to track my weight loss and gym routine. One week isn't going to kill you, it might throw you off your routine. Considering what I just said, Don't let it continue any longer than a week, because then your going to be in danger of seriously getting off track. When your off track, your not hurting me, or anyone else, your hurting yourself. I heard these words before and I think about them all the time "You cheat your body, your body will cheat you!" I think about that every day I think about quitting.
Keep up the hard work, don't quit, and always look ahead.