Boyfriend problems.. Please help.

Alright. We've been dating for 8 months, happy as could be. He broke up with me while in the middle of a softball tournament, bc i couldnt text him back . I've been playing ball since January & this happened about a month ago. It scared me that it was that easy for him to break up with me so i asked my mom & she said dont go back for a little while. My best friend Coby which is also his friend since only of this year, decides he has feelings for me & starts to talk to me more, i see nothing of him in that way & he kissed me at a baseball game . I was shocked told him i cant do this & i left. My ex found out . We are back together but he keeps holding it against me & wont love me like he's supposed to. I feel he's using me... Should i just, break up with him? Or continue to be sweet & loving like i've been doing