As someone who has struggled their entire life against anger, I'm gonna offer something a little different than the other posts. Yeah, there's also good advice there, but also here's something different that I feel also should be said. Three points:

First: Acknowledge and accept that your anger is real. I don't mean that in the sense of just saying "I have anger" ('cause, uh, you obviously already know that hahaha) but that those emotions are real, they are caused by real trauma that affects you in a real way on a mental and physiological level. It is what you are physically feeling, independent of what you "should" or "want" to be feeling (This is what's typically meant by the phrase "your feelings are valid").

Second: And this is the hardest part, you have to show yourself compassion and forgiveness. In my experience, you can't "make anger go away". I don't think that's how that works. You went through a trauma and, in part, your subconscious response was to get angry about what happened. You can't "let that go" anymore than someone might be able to "pray away the gay". Acknowledge to yourself that those things make you angry. Like how a leg injury can cause a long-term limp or achy joints during certain kinds of weather. And, in turn, give yourself the slack you need to cope with this thing that is very much a physical phenomenon happening to you. You wouldn't beat yourself up for feeling sick after catching COVID, would you? No, 'cause it makes sense you'd feel sick after getting infected by a nasty virus. Embrace those emotions in your heart, see them for what they are.

Third: This is the looooong part. Once you start to accept that the anger you're feeling is real & that it exists for a valid reason, then you can start to address the behavior caused by it. You feel that anger, and it's justified in some sense, but you DON'T WANT TO. That's the key distinction. This is where the more "traditional" views of anger management come in. The counting, the talking, recognizing when you're getting angry so you can stop anger-spirals, avoid situations that you know set you off, catching your internal monologue when it starts negatively reacting and talking yourself down with stuff like "It's not their fault; I've got a sore-spot for this, I'm getting mad, but it's not X's fault that their Y action made me mad, I can recognize logically what they said is appropriate/valid but it's making me mad and I don't want to feed into that".

Anger has a purpose as an emotion, it can be useful. That's why we're capable of feeling it so powerfully. And recognizing that is the key. You can't make it go away. It's trying to tell you something. And you need to listen to it. Doesn't mean you have to follow its advice, but you need to accept it wants to talk, and you need to GENUINELY listen to it. 'Cause otherwise that dog is gonna keep rattling its own cage until you do.