I cannot recommend mindfulness enough, as already suggested by many others in this thread.

I think, you said you are already in therapy? In this case, I would definitely talk with your therapist about this and things you want to adopt beforehand. If you want a simple concrete tip, you could try the “mindfulness coach” by the US department of veteran affairs. I liked it a lot and the apps from there get good privacy recommendations from mozilla.

I am a bit suprised by the many people recommending to just stop giving fucks. Is this what you really want? Or do you just want avoid the emotions of taking control?

You do not need to be that hard to yourself when your feeling “wrong”. Yes it is probably better for yourself if you don’t overreact. However you cannot really cotntrol your feelings. So it is still better to accept your anger. First, as you said, it drives up the frustration, because now you are also worried about your feelings. And second your original emotion wants to be “noticed”. I read and experienced a few times myself, the “wrong” emotion disappears often quickly when you accept it. It is an essential concept of mindfulness, to accept your emotions.

Edit: As far as i understand it and experienced it, saying to yourself “no i shouldn’t be angry about this” won’t change your thinking