Disappointed in myself

I keep screwing up, everything I worked for I keep messing up. I am back tracking so badly and I am not sure how to fix it. I have gained back a lot of weight that I need to remove it. I need to get back to what I was at Rhea's wedding and that is going to happen. I screwed up on my 100 days and I am going to restart it. I will succeed. I have made goals before and been able to keep them, why am I having such a hard time now? My personal goal is to be down 26 pounds by May 18. I want to be be below 200 again; the amount I swore I would never be at again. I have to change some habits I have picked up.