I found some conversations on my boyfriends facebook?

[Cam]

So, yesterday my boyfriend left his facebook open and I was so curious that I browsed through one of his conversations that was with his ex and well he asked her if she was seeing someone and she said no and so he replied that if it were for him he would split himself in half to be with her...and then I found another one with another girl saying he had been thinking about her and going through her pictures on facebook...i dont know what to do, because I know he's a flirt, and I asked for him to stop, but this crosses the line and I feel completely disrespected, I am upset, but I don't know how to confront him about this, especially since I got on his facebook when I'm really not supposed to...thanks