I can honestly say that I have felt like this many times. Controlling one's emotions is very hard especially if you don't talk to people about how you feel.
I have recently learned that the mere act of speaking allows you to see and analyse things in a different way or it may allow you to make a good decision. Therapy also helps a lot, to my mind.
From where I am standing, experience, as well as knowing my self better have allowed my to feel better or to be in control of my emotions.
I guess that what worries one is the past and future but we forget about the present which is the only time that really matters. The only moment where we are actually living. The past will never be changed so we just have to let it go. The future doesn't really exist.