I Am Feeling Down

Some people make me upset. They don't understand how I feel at all, and thus are so disrespectful, though unknowingly. I guess it's not really their fault, but I don't know how to make them understand how I feel without being randomly rude out of the blue. My (almost) my whole life, I've lived by the concept that although you can disagree with someone, you don't ever have to be rude, and you should forgive them quickly, so they themselves can learn. But, sometimes I just want to scream at people. I always hold it in though. How could I possibly hurt the feelings of another, as that would violate one of the only three morals that make up my identity. Without even one of those morals, I don't know who I'd be.