Problems with my own personal confidence. Need advice.?

Most who know me would describe me as the most outgoing and self confident man that they know. And i used to believe that it was true. Everything was good for me till about 2 months ago. Before the event my girlfriend and I would make out and do things that most couples do, save for sex. She is a virgin which ties into this whole point. About 2 and a half months ago she started texting me wanting to have phone sex. All well and good for me i was game, nothing wrong with that idea. And that happened about 4 times total. Well two months ago struck and we were in her living room, nobody around to hear us, and she finally broke down and brought the perverbial subject up. "I want to have sex before marriage". It at first seemed very easy for me to shrug off. Now dont get me wrong sex is great, my last one was nothing but, but this one i dont want to take the chance of ruining by complicating it with sex. I dont know if it is the fact that i am scared to loose her or the fact that she is the most beautiful girl i have ever known, but for some reason my mind immediatly began searching for excuses for why we cant do that. the only one that came to mind was "how would we pull that off, your not allowed at my house, and one of your parents is ALWAYS home." seemed like a solid ender to the controversy to me. Well she must have been planning on saying that to me for a while cause she had immediate counter points. "well next time we go to the movies we can do it in the back of the car." ****!!!!! well she had a solid point and i know that next date is show time. and as you might guess, we havent gone on a single date since. she really hasnt noticed too much the sudden lack of going out and doing things, and if she does she doesnt care enough to mention it. she has however began to show her displeasure to me not taking her places by grabbing my junk every chance she gets, and doing sexy dances when we are alone. everything she could manage to provoke me into carrying her to my car and being done with it. i dont know why i am fighting this so much. i am so self confident and prepared but i feel so nervous. every time she has brought it up my heart accelerates, my my races. i havent felt this nervous in years. what should i do. i know if i deny her strait up and say i dont think i want to have sex till mariage then she will be very upset with me, and as weak as that sounds anyone being upset with me destroys me and breaks me down into depression. i need a solution that doesnt hurt her or me.