That is very true, if your bf was really paying for cam girls and wanted to hide the fact from you, he prolly would've erased the history so it may be a secret, so it was more than likely a spam pop up.
And for your other issue, communicate, that is the key to a healthy relationship, bring up the topic casually while watching tv or something...you can tell him 'these fantasies' as one of your friend's and observe his reaction that is whether he gets aroused or not...you can still talk to him as long as he doesn't gets disgusted at the idea.
To be honest judging him merely by internet history is not fair
~C R