I have anger issues from my parents' divorce.
It took a long time before I really thought honestly about it and started seeing a therapist. That was a great decision- she wasn't the first one I'd been to- you have to find a therapist who suits your personality- it's kinda like dating!- otherwise you are wasting your time.
As for letting go of the past, I try to learn something new- a skill or some geeky thing even- every year sort of forcing myself to become a little different person than the year before, so the past doesn't mean so much.
When you feel like you have outgrown your past- the way a lobstah sheds its shell- you can just walk away and look at it like, "huh, that used to be me? Well then."
And keep on walkin'.