First, I really feel for you, since I recently left high school, and though I wasn't paleo, I've always been different in many ways and have had a hard time fitting in. I think you'll have to just wait - school is a nasty environment, especially for people who are different. At school, people stare, poke and laugh; its easy to understand, since everyone has to go to school, while most college students make the conscious decision (I'm talking about emotional maturity here, not dietary habits) to go to higher education, so the level of potential abuse is lower - you simply have a wider pool of people to deal with in a school.
What you have to tell yourself is that the people who ridicule you now are of no consequence to you. It takes a long time to find good, real friends, to find company that suits you, people you would want to spend time with rather than just doing it to 'fit in'. Although this might sound cliche, you really need to ignore snide comments and remember that a lot of these people actually, deep down, envy your self-discipline.
Why do you think a lot of people take it so close to heart when you refuse cake or a similar non-food? Because deep inside, they are jealous of your ability to turn it down; you eating it would make them feel better, feel like less of a failure.
Now as far as conventional wisdom brainwashing, I agree that its infinitely annoying. I deal with pangs of misanthropy on a daily basis; it annoys me to no end when i hear people at the gym discussing 'healthy' wholemeal cookies, and it similarly drives me up the wall to see people mindlessly shoving cake in their faces and then complaining of weight gain and health issues. It also irritates me when people look me up and down if I ask for full cream in my coffee. One of the 'negatives' discovering this lifestyle has had for me is that I have noticed that I've become rather arrogant around people who allow themselves to be brainwashed, and people who have no willpower. There, I've admitted it, go ahead and hate me, but we all have negative aspects to our characters, and I'm no saint. I'm still working on the arrogance issue, because misanthropic feelings cause stress.
It really helps to focus on yourself, and those close to you. I know it sounds egoistic, but this really has more to do with self-preservation; go to great lengths to get your family to be healthy, and look after YOUR body the best you can; after all, you only have one you, and you want it to last and thrive. You can't save the world, and other people will make their own choices, and pay for them.
Best of luck!