My girlfriend is very upset and hurt,she is saying she might leave me!!!?

She probably feels like you violated her privacy by going behind her back. That's something that most people can relate to, how would you feel if she started investigating your actions without asking you about it? Really, there isn't anything you can say to take back what you did, you just have to wait until she cools down. You have to prove to her that she can trust you, there's no easy way to do that but let her know how you feel without overwhelming her and invading her personal space. You have to be persistent, but don't be clingy. If she tells you she doesn't want to talk to you, tell her you understand and that you're sorry for what you did. Always be attentive to her feelings and what she wants. Remember, you may have both messed up but you're the one looking to win her back so don't bring up her mistakes until after you've worked through yours. It's really just a waiting game. She may not forgive you, you did go behind her back when she asked you not to. But she may forgive you in time. Not much you can do but wait it out.