Yes, fasting will not only detox physically but also mentally. When I was young, I used to be very angry and planning revenge when someone did something wrong to me at work. But was seldom acting on my thoughts and carried those negative emotions with me. When I learned to do long fasts, I also cleared up those stored emotions and became more forgiving.
Fast away, it may take many fasts depending on how old and deep those emotions are seated. You can cry on your own without even fasting, it is a good thing.