What do I do about being constantly harassed?

Almost everyday I have to put up with 3 girls who I HAVE to sit next to in Math class who constantly torture and harass mentally me every single moment they can get. What I don't understand is why 2 of the 3 are against me, because I've never done anything to them and one was even my elementary school friend. Its getting to the point where I want to run out of class and cry my eyes out in the washroom. I try my best to ignore them but its hard if you're sitting trapped in the inside seat corner and you're treated like a piece of ****. I don't know what to do anymore.