I'm with golden eye on this. Society wants you to believe that "it's just a guy thing" so that guys have that excuse to indulge. I definitely would not be comfortable with that... I too struggle with body image, so if I knew my guy actively looked at and engaged in internet sex chats it would rip me apart. To me that's cheating, and worse yet it's with much hotter women than I could ever be... Porn is one thing, and I'm not comfortable with that either, but the live cam chats would definitely be a no-go for me.

This is about you though, so you need to decide what you're comfortable with. If you're not comfortable with it and it doesn't gross you out enough to break it off without giving him a chance to change, then ask him about it. He might not be willing or able to change it though, so you might have to consider if you can handle it if he can't change.