Hey, ANNE-MARGARET !!
Take a deep breathe. Everything is going to be okay. You can't keep beating yourself up because you aren't perfect. You don't have to be perfect to be healthy. Which may be part of your problem. Don't try to do everything at once or you will end up frustrated. Remember, you're trying to change habits learned over a life time. That's not going to happen overnight, a week, a month or even a year. Change takes time. Thus the need to be patient with yourself and your body.
One thing I've learned is that if I have a "bad" day during the week, that doesn't mean I should chuck the rest of the week. As the cliche goes,"don't throw the baby out with the dirty bathe water". If you were to eat right 5 out of 7 days this week, you'd still be doing better than the average American.
Think progress instead of perfect.
Start with small changes and achievable goals. How much are you trying to lose ? Let's say you want to lose 50 pounds. Don't think of this as having to lose 50 all at once. Start with the first five pounds. Lose that five and then move onto the next. You'll find it easier to break up your weight loss into smaller bite sized morsels. pardon the food pun.
As for gaining weight overnight, I can easily "gain" 3-4 pounds in a day ! Is that a fat gain ? Nope, it's nothing more than a temporary water weight gain that passes in a few days. In order to truly gain one pound of fat, I'd need to eat an extra 3,500 calories on top of my normal daily intake.
Your weight is not a static number. You will see many ups and downs day to day. And that's perfectly normal. So, don't beat on yourself because the scale goes up 3-4 pounds in a day. that doesn't mean you gained fat. I person can gain weight without changing their eating habits. It's all about those water fluctuations. Ever notice your weight goes up during TOM ?? Most women tend to gain weight during their menstrual cycle. Is that a fat gain ? nope, that too is nothing more than a temporary water weight gain that passes in a few days.
Don't tie your emotions to the scale. there really is more to good health than a number that stares at us from between our toes in the morning.