I think it is really great that you are interested in your Faith at a relatively early age.
We live in a materialistic world with a material, hedonistic culture.
You’re discovering that the moral teaching of your faith clashes with the Way of the World.
Look, the people who try to follow their Christian faith has relatively always been a small part of the population.
You know that human beings are fallen because of the Original Sin of Adam and Eve. That explains the sinful nature of people in this world.
There’s nothing wrong with being religious; following the Teaching of Christ and friendship with Christ is the greatest gift that has been given to mankind.
Unfortunately, we live in a very secular American culture, and much of the Protestant morality that existed in our society has been and is being dismantled and attacked by Hollywood, secular Humanism, human greed, etc.
The secular news media and movies, whose goal is to make money, on the whole, won’t affirm and will attack your Christian moral beliefs.
You shouldn’t be afraid. Pope John Paul II said “Be not afraid!” when he became Pope.
Your decision to follow Christ and his commandments is based on Christ’s Truth and Catholic Truth.
Drinking alcohol to excess and sleeping around may give people a feeling of temporary pleasure, temporary happiness, but it is only temporary.
The same with owning many material goods, being popular, having a lot of power over other people.
Only belief in God will bring real happiness, but we can never really be truly perfectly happy in this world. As St. Augustine writes, “Our hearts are restless until they rest in Thee,” but we can be reasonably happy, joyful in our faith.
If you follow Christ, you will face ostracism from others. In the Sermon On The Mount, Christ says blessed are those who persecute you and revile you because of your belief in Him.
But we must be willing to suffer, because Christ suffered for us.
John Paul II wrote of a “White Martyrdom” that modern Christians may face in the modern world.
So, there really isn’t an answer to your question. The modern world hates anything that may pain or suffering.
Catholicism sees human suffering as an instrument that draws us closer to God.
So, if you follow Christ, you may have to experience some sort of suffering, ridicule, or persecution because of your Faith.
Many of the Conservative Protestants see the ridicule and challenges from non-believers as a sign of the Christian Truth of what they believe.
If you want to earn some Grace, you could admonish (with gentleness and charity) the sinner (a Spiritual Work of Mercy).
However, you are not obliged to speak or talk or associate with anyone. I just wouldn’t say anything, and go to your next class or walk away.
If you can bring a Discman, Radio, or Mp3 player to school, you may want to listen to music or Catholic Radio instead.