huge mistake, super sad

So... I know this is really stupid, but I looked at my boyfriends phone the other day. things have been different between us and I was starting to get suspicious, so I was like “it wont hurt.. especially if I find nothing.” the first thing I do is go to his snapchat and... it says the last conversation he had with his ex was 21 weeks ago. we started dating 24 weeks ago. when I tapped on the chat, there are saved nude pictures from her still in the chat and I felt so wrong I immediately closed everything out without even looking at dates, reading any messages, or going any further. its just been in the back of my mind ticking and I cant stop thinking about it. I just want to cry. am i a terrible person???