Most Helpful Guy
It sounds like he is still very immature. First of all, breaking up over the phone is the lamest thing anyone can do and is disrespectful to you. Second, showing his "Friend" how you "act up" by calling you and breaking up with you is complete bullshit. What probably happened is that he was with a girl who was taking interest in him but knew he had a girlfriend. So what he decided to do was call you and break up so that he could show that girl that he's now single and interested in having intimacy with her.
He sounds like a very fickle, self centered, immature, disrespectful prick and I would highly recommend you respect yourself more next time than to allow someone to stomp all over you as he did. Do not ever let a man try and make you believe that you are in the wrong for "having an attitude", he is not your parent or your employer he cannot tell you how you should behave or feel.
Tell him he is disrespectful to you and that he lost his chance to be with you that day when he called you on the phone to break up with you while with another girl who would be so rude as to say "he will talk to you later" like she owns him or something. After you tell him off, never talk to him again and move on. You deserve better.
Most Helpful Girl
He's playing with your feelings. He is immature. Walk away and find someone that will treat you right.