Adolescent 17-year-old here, it is actually my greatest fear. But I do not have the healthiest mental state.

The liberation from this fear comes in a somewhat disingenuous way: humility. I'm not saying that as a slight against you (as if you are proud) in any way whatsoever. Nor am I espousing humility as a sort of passive acceptance of "the way things are." But by recognizing, patiently overcoming, and forgiving yourself for your weaknesses and struggles -- and by offering others the same -- you will find that, over time, this fear will lose most of its strength.

Furthermore, you won't be offended when others judge, reject, or humiliate you. Instead you will feel a sorrow for those who live in such a way, a sorrow that can hopefully be nurtured into compassion. If this sorrow turns into a holier-than-thou attitude, though, then we have a problem. :) The way to avoid this is through honest recognition of one's own weaknesses; once again, humility.

Emotions and opinions are fickle; the way people treat others reflects as much about the struggles and burdens they bear as they do about how they might "really" feel about something. To make ourselves beholden to other people's opinions and judgments is to necessarily strap ourselves to a roller coaster.

As someone who used to struggle with this a lot -- albeit unconsciously, because I was the one who was harsh towards others -- this is my experience.

College offers you a much larger group of people surrounding you, so it's harder to judge everyone. And in turn, you recognize that people are judging you less. This is part of the freedom that you feel when you exit high school, I think :)