Moderation

Moderation is a work I need in my vocabulary... I am now aware of this.  I decide to turn my life around and go vegan... If feels amazing!  I feel great eating solely veggies.  My body starts changed. It works great for a few days and then I binge on cookies.  I don't have a beer for a week or 2 and then I have one drink... than 2.. than wake up to the worst hang over ever.  Why do I see the world as so black and white?  Either I'm a vegan today or a fat slob binging on wings and beer?  Now that I'm aware of this how do I work on moderation?