Girlfriend has received pictures of another guy?

you have to do the only thing you want to do. you have to confront her about the things she is lying and hiding from you. print all those messages and comments and then confront her. tell her that you don't like the things she said and if you want to leave her, you just have to say "I'm done, it's over, we are through," make sure she doesn't have any of your passwords, keys, or possessions. good luck.