Please help me out!!!?

ok so my boyfriend is really nice to me when we are alone then in public I am a total stranger to him. I tried to break up with him, then the next day he still calls me baby and kisses me, then we get to recess he tells me to go away. and he always needs me to help him cheat on tests... but when we are alone we cuddle and makes me feel like an angle... but am I being used? How can I make him understand that we are broken up?