Hi neweyes.
Though I work in the mental health field I'm not even going to pretend to be an authority or really know what I'm talking about. I'm not going to bore you and try to explain the dynamics of anger or the other detrimental emotions that may give anyone problems with improving their lives in some way. I'm very new here so I don't expect to have much influence on anything.
What I will do is offer a couple of suggestions that will serve to help you begin to work through the anger that has resurfaced after a lengthy dormancy.
Someone has already mentioned journaling. That's a great idea though I would have just called it writing down your feelings. I find that writing such feelings of emotions serve to help identify their nature and once identified will lead to their exploration. This would likely occur with the help of a therapist. Such exploration would inevitably lead to discoveries about your anger which will in turn cause the anger to lose it's grip on you (just my theory, I could be wrong).
This process involves learning important enough about the experience to evoke meaningful emotional and spiritual growth.
The other suggestion is to try your hand at poetry. Poetry offers amazing and untold therapeutic benifits. I knew someone who did just that and wrote some amazing poems because she herself had been abused by her father. She had the courage to testify against him when no one else would and it led to his conviction. Apparently she was not the only one he abused.
My point is this is something you could try doing until you see your therapist. Best wishes on your endeavor if you have not yet begone the healing process.