help?

Me and my boyfriend have been together for about 1 year and some months. We have fought multiple of times but yesterday was the biggest fight we had. I was looking through his phone and saw a picture of a girl naked in which he deleted but I clearly saw it still there. I had no clue what to do and he didn't give me any explanation till 15 minutes of me crying. He said that the girl in the picture was a girl that was sending nudes for money and that he didn't believe it so asked his friend and his friend sent him the picture. His friend knows we have been dating and I'm a good friend with him as well. I cried not knowing what to do so I said I was breaking up with him and he said he was sorry and that he needed me and got so mad to the point he broke his phone he threw his phone onto concrete. I went back with him but I don't know if it was the right thing to do.