Porn videos

So, I have a question. Recently by accident I stumbled upon some videos of my SO and his ex. They were pretty graphic ( I didn't watch them, but I saw the first image).

I felt suddenly cold and started shaking, I wasn't mad, I think I was sad.

It has been a week, now I'm angry and hurt really hurt.

I have actually talked to him, he said he didn't know they were there. I feel it deep down he didn't erase them. I just don't know why.

I feel he still thinks about her that way, maybe I'm not that appealing to him, I just don't know. Maybe this has happened to any of you? How do I leave this behind?

He didn't delete them.

As for the videos, they were on his pendrive, the one he takes everywhere.