Cheating and not owning up

My boyfriend of 6 months had been acting really weird around me and did not want me to go through his phone. The simple thought of me having his phone led him to always change his passcode. So he finally let me go through it and signed out of all his social media accounts. I found this very suspicious, so I took the time out to go through his photos and found nudes of him and of other photos from women along with videos. When I tried to ask him about his nudes he tried to lie and say it wasn't his and that I couldn't accuse him, even tho in the photo, it showed boxers that were clearly his . I'm honestly disturbed more than devastated.