Wundawoman: I love your "location" ... Lawn Guyland, U.S.!
Anyhow, I don't have any answers that are as valid as a therapist and I applaud you for taking the step of talking to one.
However, as one with a lot of anger, I might mention something that helped me this year in dealing with some anger and the inability to let it go. Oddly enough, this came from Dr. Phil, who was doing a show about a woman who couldn't let her sense of betrayal from some person (I forget the specifics) go. She couldn't get closure. Since that is a common problem of mine, I remember what Dr. P told her ... that she needed to get that closure, whether it meant writing a letter or calling the person or whatever, but that she should do the least thing that would bring her closure ... e.g., if a letter would do it, she should stop at a letter.
I thought this made a lot of sense, but also that it opened up some issues of whether we should be contacting people who we are angry with and that are angry with us at all. Is it fair to pursue relationships that are closed for one person just to get closure ourselves? Isn't that a little like stalking? Dunno.
But the part about doing the least thing that would bring closure made sense to me.
I probably shouldn't post here because I don't know the answer and I don't think I've successfully dealt with my anger, at least in the sense that much of it is still there. I just let incidents and people go, but anger often remains.
I wish you the best! Maybe it will just take some time for the therapist and you to work this out. Maybe you need another therapist. It's hard to say, but don't give up on getting help because you are worth it.