please disregard my previous post, there was a mixup with moving/merging threads
There's a few issues here... first of all, not all submissive want to be submissives 24/7 and totally want to be in the lifestyle ALL the time. A lot of people only 'play' in the bedroom and it sounds like your girlfriend is NOT one of them. This is something you'll have to talk to her about.
Next is that it's concerning that you have snooped around in her personal emails... and also do not want her to see her friends.
Once again there are submissives who wish to be slaves and want all aspects of their lives controlled but these sorts of arrangements are meant to be talked about and agreed upon by both parties.
At the moment it sounds to me like you have major issues that need to be sorted out with your girlfriend, one of which is discussing the nature of your relationship.