Starting the "dieting" process is always the hardest part, although to me it sounds more like you need to get back into the healthy lifestyle. Just take it one day at a time, if we look at it like "oh! It will be weeks/month before I lose this weight" of course it seems impossible
start a new day and a new you with a healthy meal and when you feel like craving the bad food as hard as it is, just stop yourself. Its easy to say but omg it's the hardest thing because I still struggle with it. I myself am a chocoholic so when I absolutely HAVE to have it, I buy the bags of mini Dove 1 inch chocolate squares and eat 2 or 3 of those, at first I wanted to finish the whole bag but realizing that eating more of them won't actually taste better is what stops me. It's about quality not quantity. I'm sure you can lose those 13lb and more!
this site is of great help<3