please help.....annoying person?

There is this annoying person at school We use to be really close friends When me and my friends fight he always go with the people against me and makes it worse And when me and my friends make up He goes up to them and says what I did wrong and they shouldn't say sorry (like his making us wanto fight again) He back talks me to my friends when I'm not at school He also sits next to my best friend (and I think his telling BS about me) me and my best friend dosent hang out that much anymore, and he's avoiding me (i think because of the back talker) He is also two faced (me and friends agree) He is angry at me right now because I accused him for touching my hair he hangs around my friends so if i avoid him ill avoid my friends i told my friends about him but they don't want to start a fight he can be be a cool funny friend though What do I do