Oh frumpy, doesn't sound like you've had a good day at all.
Remember to keep things in perspective. It's only one bad day so tomorrow get back on track and continue on your journey. It's what you do after that bad day that counts.
I find it really useful to look back on my bad day and try and pinpoint what triggered by snacking, this way I can learn from my mistake eg. if I snacked because you had a visit from someone that makes you feel awful about yourself you can then work out 1. how to avoid that person or 2. what you can do so what they say doesn't mess up your plans to lose weight eg. a boxacise class afterwards!
It may be useful for you to work out what one food you can't live without and then include it in your weekly diet. For example, if its chocolate, you could have a mini mars bar or a freddo once a week (for me, Sunday). I find this works better than not having it at all, if I feel like bingeing I don't because I know I'll get that treat on Sunday.
Don't be too hard on yourself, chock it up to experience and continue on your journey - you can do it - we are all here to support you,
hope this helps,