Relationship

So my boyfriend and I have arguments to where we don’t speak to each other and some we can just past them over. So the other day, my boyfriend was wanting me to help him figure out why he was getting charged from Apple. So I was trying my best to figure out what was doing it and looking up how to figure out billing information from Apple. Once I got it figured out, I was scrolling through his purchases and realized that there were apps where you talk to other people. I read them aloud and he began to get upset and mad with me telling me, “you don’t pay the phone bill, so who does? Who does??!!” I get upset and trying to figure out why he would act this way. He told me that he downloaded the apps because we got into an arguement and he wanted to talk to someone who would appreciate him more than me. He wanted to do it out of spite and for me to find it. We texted that same night and I told him not to worry about it because I’m not really worried about it. But ever since then, I have thought so much about it and I have so much animosity towards him, to where, I guess, I am being rude and unappreciative of him. He claims he never went fully into talking to anyone and never chatted with anyone. I believe him but I just don’t like how he would do that. I have never went behind his back to speak to another male and this just caught me off guard. How do you think I should feel after the things he has told me about the apps? Or should I not worry about it? Do I have a valid reason of being this way? I just don’t know anymore.