I've yet to encounter another person who experiences such immense irritation when around others, so I thought I must reply. For myself, the irritation is mostly due to "feeling crowded". I cannot stand a multitude of people and movements and chit-chat all hovering about me. I don't like when others stand too close to me either, though the distance necessary depends upon the individual and how "clean" they feel to me. I become so very aggravated. Pissed off, really. My family are the main source of this frustration, but that is because I happen to be around them more. As an adolescent not yet aware of the reasoning behind such irrational anger, I would simply become furious when my personal space was invaded. Now, I have learnt to communicate my feelings and explain what causes me discomfort. This alleviates some of the problems, though not all, as there are still instances in which I am forced to be around a lot of people. Working, grocery shopping, and the holidays, for instance. There are some days when the thought of interacting with other people brings upon me an unbearable tiredness, and it is on these days when I may "snap", as they say, and behave rather rudely. I suppose it is the only way I know how to communicate my desire for people to leave me alone. In public, I usually rush to an empty area and sort of stay there until I can discern a pathway with less people. I also keep my gaze fixed upon the ground and do this sort of odd hum, which I'm sure must seem odd to an onlooker. Again, this is a way I communicate "get away", I suppose.
And then there are, what I refer to as my "f**ck it days", where my brain just decides it's had enough and forgets how to hold even the most basic of conversation.
What a lovely-albeit longwinded-story Midday, but what, pray tell, was your point? You may ask. Be patient, I say. I was nearly there.
The only way to deal with this frustration is to delve deep within the crevices of your mind and determine the main cause of your irritation. You mentioned a dislike for humanity as a whole-a trait shared by much of humanity, funnily enough-but what is the reasoning behind such detestation? (Perhaps too strong a word, I know.) If it is simply due to the fact that humans, as a whole, are pretty awful, then I believe you are wasting precious energy. Brooding over the rotten nature of others will cause no change to occur. People will continue to hurt others so long as they have something to gain, be it something tangible like money, or something as simple as a boost in pride. Such is human nature.
I've gone off one a bit of a tangent. There is a reason for everything, and therefore, a deeper reasoning behind your bitterness. If not, you've wasted quite a bit of time.
Find the source of your irritation and share these reasons with your family so that you may spare yourself, and them, future discomfort. It isn't fair that you should live constantly irritated, and it isn't fair that they be the objects of such negative emotions without knowing why.
Hopefully a bit of the above makes some sort of sense and is found helpful.