Want to learn to ignore things. As well.

You not willing to keep quiet when you see something wrong is not a bad thing.  The way you react or respond or handle would have been impulsive,  aggressive and without realising the consequences.  Train yourself to alter the method, one of the effective tool miss being assertive, talk about that particular incident without being harsh with that person, not blaming or finding fault at that person. Focus on the issue/incident and it's effects. When required learn to ignore, no one can be perfect around us and that includes yourself also at times. There is nothing called flawless world. Be a witness for such things than being a part of those, in order for you not to take it personally and prude in your mind. Work on managing emotions as they will have direct impact on your mental and physical health. Meditation,  Yoga, exercises etc will gradually bring peace to your mind. Also will strengthen you to handle issues around you amicably.

If you still need help, consult a Counsellor in your city.