My friends are backstabbing jerks and they talk about me behind my back what do I do?

So i have two "friends", they completely mess up my life. One says something behind my back, the otherone tells me all the mean things she said. When I confront her about it, she denys and blames all on the other one. Im so tired of this, all of this is messing with my grade, my life, and my free time. I told both of them Im not talking to them and how mad I am and then they start being mean and saying how im a dirty liar. I just want peace and quiet, what do I do?