Sunny, maybe instead of apologizing use this as a tool to realize that maybe you aren't comfortable letting your T see all parts of you.... you in the the more raw forms, etc. You are so scared of being "dysfunctional" in front of him that you feel the need to apologize for your behavior. You didn't do anything wrong and there is nothign dysfunctional about anger even if it doesn't feel good when it's coming out. One thing I have learned in therapy (and am still learning) is not to be embarrassed or ashamed about the way I act in there because these are all parts of me. Me. ME. And a big part of the therapeutic relationshp is to be able to show yourself as a whole person (if if that means different parts at different times) with BOTH of you being able to tolerate it. It takes awhile. But I believe what happened to you was significant and instead of using the feeling of wanting to apologize and turning into the behavior OF apologizing, process it with him instead.
((Sunny))