Why does'nt he want to hear, my side of the story?

Sorry this is so long.My boyfriend (ex now) and I were in a lovers quarrel at work, he head-ed me, which later, he told people, (it was on purpose because he used to do it to me, all the time, outside work) it was an accident and we bumped heads, even though he's about 6'1 and i'm 5'8. I mentioned it to a friend of mine, that he head-ed me and without me knowing, he ran to the building security and told them, what I had told him. It was'nt my intentions, to get him in trouble and I certainly did'nt think my friend would run to security, behind my back. They pulled the tape and viewed it, which showed he head-ed me, but security said, it did'nt look like he did it, very hard. They removed him from the building and he is to come nowhere near me, the building parking lot or the building, during working hours because it's being investigated, he can work on weekends, because i'm off,but outside the building grounds, they can't do anything about it. I could'nt go back on my words, by calling my friend a liar, once he told the Supervisor's about it. My ex does'nt even want to hear my side of the story, he blames it all on me, even though he was told by someone else, I was'nt the one, who reported him. He talks to the guy, that reported him and is well aware, that he reported him. He won't take my calls, my text messages or anything and it's so unlike him, to listen to only one side of the story. This is a man, that once claimed he loved me and yet, he refuses to hear my side of the story, I finally gave up and quit texting and calling him, because I was feeling like, I did'nt even exist to him anymore.Why does'nt he want to hear my side of the story?