A lot of times therapy makes me angry too. I think it's because I get so angry with the way my life has turned out, with my mental illness and with myself for not being able to prevent it. Talking about how I feel makes me angry, because I feel like I should have been able to prevent myself from feeling the way I do.
My point is, though, that I think determining the source of your anger is the first step to dealing with it. Your anger can often be worse when you don't know what you're angry about. If you do know, it's easier to control it. Maybe you try talking to your T and trying to determine with her what your anger is stemming from. It might really help you out.
Just know that you're not alone in your emotions. There are a lot of people who can relate to what you're going through.