Saw flirty messages on my boyfriends facebook

So my boyfriend left his facebook logged in on my computer and initially I just logged him out. However it saved the password and so I got tempted to look, more just out of curiosity than anything. I know that I shouldn't have done it, and I really wish I hadn't, so please don't tell me that.
But anyway I saw some messages between him and a female friend that he's had all his life which made me a bit uncomfortable. The messages were clearly jokey but talking about how they'd have sex if he was single. I'd like to emphasise that is was obviously a joke, but still not appropriate. He also called her hot etc. He was planning to stay over at her house and sleep on the sofa, but she said they should sleep top to tail in the same bed. They message most days.
It sounds odd but I do trust my boyfriend but these messages made me uneasy because they wouldn't say that around me. I keep trying to tell myself they're just joking but it just doesn't feel right. I really want to stop looking at the messages, but I also sort of want to keep looking in case they say anything more. And I don't know how I can bring it up without admitting I snooped.

Put the internet to work for you.

via Personal Recipe 2629979