Why?

Why, oh why can some people be so damn rude. It takes a lot for me to be assertive and confident with my actions, so when I do so and am greeted with the height of rudeness it just makes me plain angry.
When I feel angry, all I want to do is cry.
I gave a lot to that work placement only to end up being treated like shit. Thanks..
I hate conflict, and I hate being made to feel like I'm in the wrong. I'm not. So why has this completely and utterly broken the lovely week that I was having?