Just because you didn't do well on one meal doesn't mean the whole day is lost. Get right back on track with the next meal and plan on skipping any snacks that you had planned for the evening. This should help balance out your calories a little. Try getting in an extra walk even if it is only for 10 or 15 minutes. Something is better than nothing.
I read about your slip on one of the Challenges that we are on together.