I hate that!!! I was like that for a long time!!! My mom ended up giving me a book, "how to win friends & influence people" Those are not my normal reading matierals by any means, but I knew I had somewhat of a temper problem, and I read it
it worked!! I have chilled out a lot, and learned more professional ways to tell people to shut up, without being offensive or rude
but try that!!
as for the stewing over things...Try to think about things this way...If you are gonna look back on a later date and laugh about it...might as well laugh now!!! Or also, do I really want to let that stupid person ruin my entire day!?!? no way, Im better then that, few deep breaths, be thankfull thats not me, and continue on with my day