Mean girl

I am mean, meaner as I age. don't know why? I used to be this really sweet and nice person. but now, I often find myself having a hard time tolerating people I don't like. and I got angry, always want to confront people, give them a lil' attitude of mine. you can ask my roommate, he must think I am a b*tch, well, I guess he deserves that. anyho, the point is, I don't want to be mean, I don't want to be angry , and I don't want to feel guilty after I treated somebody badly, it's getting a little old. Sometimes we got angry before we know the whole story. why did this person do such despicable things? because they are born evils, or are there any extenuating circumstances? my roommate kept smoking in the room despite my numerous warnings, why? cuz he is a jerk? OR, maybe he's tired from his night shift at the restaurant, but that didn't cross my mind when I banged on his door and scolded him with a cold face. There is a quote, says "resolve to be tender with the young, compassionate with the aged, sympathetic with the striving, and tolerant with the weak and the wrong, because sometime in your life you will have been all of these." How true!