I've been angry with my T on a few occasions, sometimes because she made a mistake and sometimes because something just rubbed me the wrong way. Once I came back to a session furious about something that had happened at the previous session, and I could tell that she had no clue why I was upset (which certainly didn't help!). I have found it quite helpful to express my anger, even when I know it isn't rational anger. Usually in other relationships I tend to just apologize and try to forget it, which isn't terribly healthy, particularly if I'm apologizing for something that I shouldn't be. Your therapist should be able to help explore your anger without responding to it emotionally (like getting angry back), and help find a resolution that makes your anger feel safer to you.

If you're ready to express anger with your T, it might help to tell yourself that you're going to keep going back and working through it rather than quitting therapy when you're upset. I came really close to quitting when things were at their worst, and I'm grateful now that I didn't. Working through tough stuff with the right person can make the relationship stronger, which seems like a good lesson for outside relationships too.