If I'm not supposed to know about it, then I probably should stay out of it. Is it even about me? If so, then is there anything I can/should do about it. If it isn't about me? What am I angry about? Is it the having been left out of knowing? Why do I feel like it should have been told to me?

I guess what I am saying is think your thinking through. I am a believer that HOW I think about something and WHY I think about it pretty much drive my emotions. If I can reality-check my thinking, often that calms down my emotions.