Samnella- welcome on board, but first I need to wag a stern finger at you!
You haven't been 'bad' all day at all. You made a combination of 'suboptimal' food choices or excessive quantities; and/or you ignored your body telling you you'd had enough!
There are no bad and good foods, there is just food.
It's really worth looking at Paul McKenna ('I can make you thin' rather than 'Gastric band', imho!). The ethos couldn't be simpler. It amounts to deep eating awareness and reconnecting with 'hungry? ->eat; full enough? -> stop'.
As I've already said, I am not quite comfortable enough to not weigh or totally disregard calorific values (malt loaf v. rye bread...) so you are welcome to snigger at my pontificating above ...
.. but I am oh-so-trying to put my fork down between every mouthful and really sense each mouthful. At least 20 chews. Every time I look at available food (snack-wise in particular), I think, among other things, 'OK, am I actually hungry or am I bored, or am I reaching for it because it's there?'. I may choose to have some. But I have to remind myself not to decide how much I will eat before I start (as many diets recommend) but I try and focus on my 'have I had enough?' reflex. Not necessarily 'Am I full?' (to PMc standards which is 'just full') as, if it a snack, I don't want any nearness to full, I want 'curiosity satisfied, yes, it's good, it tastes great, I've enjoyed the small quantity I've eaten but now, so as to not undo all the other good work I'm doing, I have to walk away from it now as any more is flying in the face of my new awareness, and here I go!'. I am working on this. Wine is not a good idea, as, guess what? one's ability to rationalise quantity and calorific value is oddly distorted by a glass or two. Who knew? 
Do not dread being a bridesmaid, see it as a fortunate opportunity to beat this stupid weight thing. When is the wedding? How much would you like to realistically lose? How much will bring you to a BMI of 25? Focus on that dress and how good you'll look in it!
Hadn't thought about G&T v. wine! Thanks spruced!
And I shall be taking a rollcall of all you lot next Friday! Stand by your beds scales!
And keep posting.