I need help with this relationship problem. Plz help me. somebody?

I have a girlfriend who i have been with for over a year. She didnt want me to get a facebook and didnt tell me why. so after awhile i got one cuz everybody kept asking me if i had one. im down at college two hours away and she is a junior in high school. While down at hocking i met a girl and we became friends but even though we had each others numbers and was friends on facebook, i didnt tell my girlfriend cuz i thought it was nothing. Anyways this girl named jess that i became friends with had a birthday so i bought her a one dollar card cuz we was friends. I also sent jess an email asking when we could meet up cuz i had a surprise. the surprise was a card. Well i eventually gave her it in a class. Well anyways my girlfriend found out i had a facebook and the emails between jess and me and also that we was friends and i didnt tell her. So now she is mad at me for lying and hiding things. Also she posted a note to jess calling her an ugly ***** and used my facebook to do so. So jess tracked me down and asked what the hell that was about and i told her about everything that happened but i told her that my girlfriend and i broke up two weeks that me and her became friends which wasnt true. So she said my girlfriend can call her and she will striaghten things out. If she does then jess will find out i lied to her and that will also piss my girlfriend off. So how can i fix this? Plz i need some major help.