To be hurt or not to be hurt

Hi,

Thanks for taking time to read this question and answering.
Before I begin, let me give you a back drop into the whole thing. I am in a long distance relationship. We both are working and committed to each other despite distance. We meet up regularly, talk on the phone daily, text, email (basically stay in touch all the time). My guy L, had a fight with one of his friends and told me he is never meeting that guy again. (He has said this a couple of times with other friends and the next time they call, he lets go of his ego and meet them up. I am completely okay with this, in fact love this quality).
So this one day, I call him up, he tells me he is sitting working on something in a cafe (this is post work). He is constantly trying to get me off his back. After a bit, I tell him I am hanging up and before I could hang up, I hear him speak to somebody. We end up having a fight where in he says he was with the same guy and did not tell me because of his ego.

My point is that if he were sitting with his friend, why didn't he tell me? I would have never come to know this if I had not accidentally heard him speak. I don't even know he was actually with that guy. What was the point of hiding stuff here and I don't even know what all stuff he has been hiding from me. So the next time he is out with/without friends, how am I to believe that he is not hiding stuff from me or he is not cheating on me? He thinks whatever happened is no big deal, I am over reacting but honestly, I am hurt for I look at this as breach of trust. If I were to do the same thing, he'd be mad at me. Another thing is I do not know how to react? If I should break up and if not then how can I trust him again?

Thanks again.