When anger is good

As I journey through my healing process, sometimes I make assumptions about things and I don't always know that it's true. Coming from a mind set of always seeking the right thing to do from someone else, I find myself wanting to discover answers for myself. Even if I make the wrong assumptions in the beginning, -I- want to make that discovery and if I find that I am wrong, I will change the answer.
Lately, I have gotten very angry when I think about incidents in my life where I was made to feel ashamed of myself and I should have never been made to feel that way. There is one particular instance where I felt that I did the right thing yet still, I was not only chastised  for it. Let me explain.
We were at Summer Camp and there was a large room, very similar to a locker room where we took showers. I was in there with other friends and for some reason, which I cannot remember, I started singing "Matchmaker, matchmaker make me a match", from Fiddler on the Roof. So my friend handed me a match which he had in his pocket. The floor was wet so I rubbed the match head on the floor to render the match harmless. I struck it and to my surprise it lit so I walked over to the sink, turned the water on and put it out. Well, someone told on me and the next day, I got REAMED. What was I trying to do, burn down the forest? (Mind you, nothing was said to the boy who had the match). I was very confused because the man who was reaming me, I thought he was the oracle of God and every word out of his mouth came straight from God. I was confused. I must have been in the wrong, how could I have done such a thing.
Shame and confusion. I look back at that now and get very angry. I feel like that incident was the beginning of what was to be my demise, so to speak throughout high school. I was always a leader and my peers respected me. That was not to be during high school.
There will be other stories like these but these make me angry. So what is good about this anger? When you can see how this effected you, you can make sure that this type of behavior does not reoccur - at least in you. I don't want to remain angry. I don't want this to be a stumbling block that I cannot get over and cause me additional grief. All of this anger has helped me not be so passive about the way I am treated. It helps me stand up for myself and what I believe in. There very well may be more but as for now, that's my story and I"m sticking to it.