There's a group of people in my class who hate me

let the school know

I used to have my head down and focused on my studies. Because of this, I didn't often talk to people unless it was about the work. Nobody really approached me in a friendship kind of way, and I was absolutely fine with that.

My problem started last year, sometime at the beginning of the school year. One of the troublemakers in my class (who had been seated next to me in the previous year and talked to me normally) started throwing pencil lead or something of the sort at my back. It went on and on and on. I thought that he might stop if I ignored him. When it just didn't stop, and I was too angry to process what the teacher was saying, I turned around and yelled at him to stop, and the whole class went silent. Long story short, he got into trouble because of me and hated me ever since.

Throughout the past year he'd slipped snide remarks, snickers and pointed at me purposefully with all his mates. I didn't really care, because I had my head in the clouds I suppose. I was too busy struggling to regain the focus I lost.

Now, however, I've become much better at my studies and started taking in my surroundings properly again. What I noticed came as a bit of a shock; nobody has my back, and there is this slowly growing group of malignant tumours who are piercing said exposed back.

They don't look in my direction, not when I'm looking. But when I'm looking away, they mutter, snicker and stare at me (I can see it from the corner of my eye). When I get an answer wrong in class, they take the mick out of me but they never do it to anyone else who answers a question wrong. In fact if I do anything wrong they'll get over-excited about it. They almost glower at me if I make eye contact with them, or they sharply look away. It's weird, they treat me like I don't exist but somehow also openly slip in ways to critisize me.

I'm only stuck with them for roughly half a year more. In the meantime, however, I still have to deal with them. I want to show them I don't care, but I can't help looking in their direction when I hear one of their mutters, or going red when they laugh at my stupidity.

How should I act around them, to make them stop? In fact, how do I stop caring like I didn't care before?