I need advice on work and the never ending feeling of not getting it!?

I have worked here for 4 years and for some reason I just can not figure out the personality insanity... let me explain today everyone is being very short using words like he's an idiot or she's is just being a *****.. when yesterday it was all happy and fun she's my best friend he's da man... I just can not keep up with it i want to just shout my door.. but well then I'm an idiot or stuck up or a *****! is this just how every place is of is there something wrong with this group can the all be Bipolar or manic depressed .. its driving me nuts i'm just a guy trying to make a living not control the human race I don't point out faults I in fact try to look as far away from them I have always believer that people that get upset with others mistakes are the ones with the most of there own.. but now i am finding myself upset but my surrounding ! why am i becoming so affected by them, how can i cope without becoming one of the unhappy collective?