I don’t know if I should break up with my boyfriend?

So my boyfriend and I have been together for almost 3 months and we’ve had a few fights but the most serious have been in the past two weeks. Last weekend he saw I told a friend our first experience in bed was not the greatest (a guy friend) which he did not react too kindly to, and made me block him, but there has never been flirting or anything between me and the guy and he verified because he went through my phone that night. Two nights ago I was drunk and he had fallen asleep behind me and I got curious. I truly didn’t expect to find anything especially after his outburst but curiousity got the best of me. It was wrong but I was so drunk I couldn’t bring myself to stop. I was just browsing through his camera roll and then remembered the hidden feature. I opened it up and I saw multiple videos of him and his ex doing sexual stuff. I was heartbroken. I woke him up we fought and he apologized deeply and says he genuinely forgot he had those on his phone. They broke up about a year ago. He seemed so genuine that I do believe him but I can’t wipe the image of what I saw away and I can’t fully believe him or know if I can anymore. I feel anxious now which I hadn’t ever before in our relationship and I don’t know if I can handle it. I feel stupid, and while I do believe him, I don’t, I want to at least but I can’t. Who keeps such a thing on their phone? And yesterday in his drunken state after our argument he mentioned how he didn’t like the song playing and if I could change it. He told me before this was the song that was playing when he broke up with his ex. I wouldn’t have thought anything about this before but why should such a thing matter about a song with someone you broke up over a year ago? I need opinions. I’m losing my mind. I am a super confident person and now I don’t feel like it.

Updates
9 mo
I want to add something for clarification. When I mean I told someone about my sex life I did not go into detail whatsoever. It doesn’t excuse what the fact that I spoke of it. But I just revealed the fact that the first time was bad and I didn’t know how to tell him it was bad without hurting his pride.
I don’t know if I should break up with my boyfriend?
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