My girlfriends parents own a house at the shore where I have been invited every weekend since Memorial Day. Her parents made it clear that I would have my own room and even though my girlfriend and I do have sex we have respected her parents rules. Its a big 5 bedroom house and the bedroom I sleep in is on the bottom floor. This past weekend I didn't go down the shore with them and probably won't the rest of the summer, out of embarrassment. My girlfriends sister and one of her friends have been peeking into the room I stay in and evidently have more than 30 pictures of me naked or almost naked. One of the pictures has me jerking off on the bed. The worst part is that both of her parents have seen the pictures and I have never been so humiliated as I am now. My girlfriend stays at the shore for the summer and I have talked to her a few times since they found the pics on her sisters phone. She keeps telling me to come there anyway but knowing her parents have seen them is just to embarrassing for me. I never saw the pictures but my girlfriend has and told me most are just of me naked getting undressed in the room. She did tell me about the one where I was masturbating and that is the worst. Her sister is only 15 and I think her friend is the same age and now suspect her friend also has pictures of me since she won't let my girlfriend look at her phone. They must have been doing this for a month or so and I never once suspected anything. I did masturbate a couple times when I was down there but not often.