LostGurl, this sounds really similar to the thing that eventually led me to therapy - because I started having panic attacks, meltdowns, rages, and bursts of emotion I couldn't control and these were really damaging to my relationship and job and, well, self.
To me it sounds like you're a deeply compassionate person; there was no reason for you to have gone all the way back to make amends and yet you did, and that's a lovely thing. So know that you feel deeply, somewhere you empathically pick up on what people may feel and you care. So the anger may seem all the more antithetical.
My understanding of anger like this, the kind that bursts out and hurts and is shortlived, is that it's coming from somewhere deep inside. I think anger happens particularly when there are parts of us that are unacknowledged and parts of us that feel unloved. Which is ironic, because anger isn't a lovable emotion. One tends to reject oneself all the more for anger. Which leads to more anger.
So... two things:
1. It's important to look at the source of the anger, the real source. This is something that needs a lot of work, and introspection, and sometimes, yes, therapy. But everyone finds their own path to it. Have you considered Vipassana? It didn't work for me, but it seems to really work for a lot of people. Link:
http://www.dhamma.org/
2. It's important to learn to deal with small bursts of anger. To find tools to work through moments when we are less than compassionate. For me what's really worked is something called Compassionate Communication - I go to two weekly meetings at this point, but it's also something that can be done alone. The idea is that if you;'re angry, or sad, or low, then it is because you have a need that isn't being met. You are responsible for your own needs, so, a) get in touch with the needs and b) find a compassionate way to express them. Link:
http://www.cnvc.org/about/what-is-nvc.html
Hope this helps. Best of luck. Also anger does get better. It's very human, it's very natural. It is like... stress, your body is telling you to slow down and pay attention.
Hugs and love!