Help/Opinions/Advise PLEASE

Morgan
So I had my wisdom teeth out over spring break and I wasn't in the mood to do anything with my friends or boyfriend. Today he was acting a little strange he wouldn't let me give him a hug because his back hurt, I offered to rub it for him and he said no. I just thought he was in a bad mood. But later one of my "friends" told me that she feels really bad and guilty but she told me that she slept with my boyfriend over break. So I went up to him later and told him that he has 24 hours to tell me what he did wrong and why he did it. I've been thinking and I think that even if he is honest and admits it I am still going to end our relationship. Is that the right thing to do? He's wanted to have sex before with me but we've only been together 4 months and I just haven't been ready, could that be why he did that? 
I don't know, I'm really hurt right now and need advice please.