snapchat????

So...because I'm really insecure because of past relationships, I snooped through my boyfriends phone a few weeks ago when he was sleeping. We've been dating for almost a year now and I have no reason not to trust him. But because he works out of state for a good amount of the year, I just wanted to see what he was doing. I looked through his pictures and there were tons of screenshots of me (which made me super happy) but hen I found a folder named "work". He is an electrician and he often takes pictures or screen shorts of his plans for the current job. I opened it...and not only were there pictures of his work stuff, but there were screenshots of this girl he was snapchatting. I looked at the picture details to see when it was taken and it was taken in September. Which was when he was away. And there were also videos of porn and really sexy woman naked and posing in provocative ways. I've talked to him about liking other girls pictures like that on Instagram because I don't think too highly of myself and it makes me feel super shitty. But since I've seen those pictures and he screenshots of that girl on snapchat, I don't know what I should do. I haven't told him. I'm not sure if I want to because things are going so great. I went onto his snapchat that same night and found and blocked that girl. It made me SO pissed off. I was really cold to him he next day.