i broke a rule and ate cookies

so i was on my diet and everything it's like really important to me and i have this whole routine of like not snacking and eating healthy food but then i got home late last night and there were these cookies in the kitchen that just looked so good and i know i shouldn't have eaten them cuz they're full of sugar and stuff but i was so tired and craving something sweet. i knew if my daddy found out he'd be really disappointed and give me a punishment but then again when i'm being bad it makes him look forward to disciplining me which is weird right? anyway the guilt from eating those cookies has been hanging over my head all day and now i feel like such a failure for breaking that one rule. it's not even worth so much stress but here i am feeling awful about a few cookies. why can't i just stick to my diet better?