Anger is a valid emotion like any other and just indicates there's a "problem". It isn't about the other person at all, it's just a mobilization of your own feelings, lets YOU know you are feeling frustrated, unhappy, anxious, etc. and brings it out in the open so it's easier to see.

Anger is never about the other person. So, if you yell at your T, it's not something your T said or did, it's an "a-ha" moment inside yourself, a lightning flash showing where you're feeling stuck. It's just another tool to help you "see". Because it signals, "problem" you (and whoever you are with, if they wish to, and one's T generally wishes to) can start thinking how to "solve". It can free you up and shift your perspective into action mode.

But anger is a feeling in whoever is angry, not an action. Violence or threats against another, etc. as the result of feeling angry is a bad choice of action when one is feeling angry. For me, when I catch myself being angry, I immediately go into interior hunt mode to see where I am feeling helpless or otherwise anxious. Then I can figure out what I can do to help myself feel more proactive and comfortable/in control. The anger vanishes when I identify the problem and start trying to solve it.