outragous scenario, might need help on this one!

Okay, I'm dating a girl who has told her mom I was the "one". We have had good history, and we have a lot of fun together. We kept dating when she went out of province to school and things were going suprisingly well besides a few fights here n there. I went up to visit her and I farked up! Hard! We went to a club one night with a couple of her friends aand things were going good. A girl started txting me, and my girl asked who it was, I froze and straight lied to her. She saw my phone and I told her what was up. She broke up with me when we got back to her room. We talked at night and more in the morning. sh1t wasn't going smooth and she couldn't understand why I was txting this girl back and why I lied to her.

To keep it one hundred with the ppl here I wasn't trying to get it in I was trying to avoid one itis. The next morning things weren't getting better so I said "you wear a cross around your neck but can't practice forgiveness"left and did my thing for a couple hours and gave her space. When I got back she sat me down and said she doesn't want to break up and we slammed all day. That eve I took a flight back to my city. I thought things were on the up but after talking to her her in the phone last night she still can't understand why I txted this girl back and why I lied to her. She said i haven't said anything to make her feel better about the situation, I got upset and told her I was gonna go to sleep and she said to get at her when I have something to say. I'm gonna avoid texting her and I don't think I'll call her tonight, but when I do what can I day to save this relationship with a sensitive girl? Thanks

To tie up loose ends, when I talked to her on the phone after I said that people make mistakes, and lying to her was something I feel like sh1t about for doing. I also explained thag I wouldn't go to such lengths to see her if she isn't what I wanted. Its hard to explain this to her and not turn AFC. One thing I didn't do was beg her for forgiveness etc. Also, when I told her I was gonna crash she got upset so the phone call didn't end well!