Waves of Sadness

I've cut out many addictive behaviours recently, and in line with what I read about addictive things, I've experienced the return of feelings of great sadness and discouragement. Seemingly without pattern, I feel utter sadness, despair, etc. But, as quickly as they are felt, they seem to go away very fast and leave a happy state. Is there any way to deal more effectively with such states of sadness and despair? I noticed I tend to project these emotions as *blame,* finding fault in everything. What does Buddhism recommend for such states?