he keeps coming backkkk

I broke up with my boyfriend after he cheated on me and lied to my face about it but for some reason he always finds his way back into my life. i haven't actually taken him back but he texts me all day & I just am so use to responding that I can't help but talk to. He honestly doesn't deserve me and I don't know why I give him the time of day. I just am still in love with him but I don't see a future. I told him maybe if he changes we could try again but I know that will never happen even if he "does change". how do i tak go him and let him know that I'm done for good? and how do I not fall for his words again? this happens every time. he talks and talks and makes me feel bad for him and bc I am still so in love I always go running back. HELP ME!! i need to stop being so naive.