Is it okay to have sexual privileges in a long distance relationship?

Okay me and my Girlfriend have agreed to be able to receive oral sex from some one else. Okay then well she told me that she is going to get this guy to give it to her. I have not acted on this yet. Well I was thinking about calling it off. The thing is that I cant though; the reason be is that I got a lap dance and I feel that it would not be far of me to call it off if I got to do that. I don't know what to do at this moment. I have this uneasy feeling that she might not just want to stop at oral and allow penetration. Please help I honestly have no idea what to do.