can i choose gay?

I met my girlfriend about three years ago. We had mutual friends, I always thought she was so beautiful and there was an obvious attraction for me. I felt it a few year ago on new years eve, I was drunk and she was drunk making out with this other girl, and although my friends, including my now girlfriend knew me as straight, i was madly jealous all night. It wasn't until about 6 months later when we got together.

I had mentioned to my friends here and there that i thought she was great but i was brushed off, for obvious reasons... Finally it all came together. We kissed, we cuddled, we became inseparable. We like the same music, food, activities, shows.. We have so much in common, our friendship is great. The best I have ever experienced... The problem?

We don't have sex. Sure, she wants too... And its not exactly that I do not want to have sex... It just doesn't feel right.
We broke for a few months last year. I sat her down and told her that our relationship was so great in all aspects except that we didnt have sex and that I did not feel gay. She was heart broken, and it broke my heart. She told me that "if only she had a penis, then I would be with her" but if i say "well if i had a penis you wouldn't want to be with me".. she doesnt agree its the same. Although we were separated, we were still in constant contact.. I love her, and I missed her and we got back together. Things were as good as before, no better no worse. Still no sex. I tried looking at lesbian porn, buying gay erotica, talking to gay girlfriends....
Its been 2 years and we have probably had sex at the most ten times. When we did have sex, i have been able to enjoy it.. But its the, getting there.. the wanting to take off my clothes or rip of hers that has been an issue...
I feel bad because I dont want to hurt her feelings, I dont want her to feel rejected, But i am rejecting her.. and I AM in fact hurting her.
For a long time, her schedule for work was crazy.. She left for work at 12 pm and didnt return home until 1230 am. I was a lone this whole time. I finally told her after one year that I felt like i lived a lone and that I just felt like I had a girlfriend who would just spend the night.. She did change her schedule and now we get to spend more time together.. which is a good thing and a bad thing..

A few weeks ago, the noise in my head was so loud i could not hear anything else...
I finally told her, I still do not feel gay.

There was this giant elephant in the room and neither of us ever want to talk about it. She doesnt bring up that we dont have sex and neither do i.. Until recently.

I have spoken with her various times about how I am feeling like I am confused and straight, she may shed a tear, then she never mentions it again. She will tell me she loves me and never wants to be without me. I am frustrated. My feelings have been dismissed and its easier to get along then break up.

Tonight, while I was at work. She went through my email and Facebook. I am not very mad about her doing this.. I have never physically cheated on her, but i have been overly flirtatious with past lovers via chat. That obviously isnt going to make anyone feel good.. at all. I am a total dick for doing these.. Please, with hold the hate mail.. I have been told various times already tonight by my lady, what a piece of shit i am.
she left, and i do not know where she has gone.

I believe that people are born gay, but i thought i could choose to be gay. I thought i was open enough, that I had enough love, that when there is a will there is a way..
There is a road block in front of me, and i don't know how to get around it.

I love her. She is funny, beautiful, kind, all these things that i adore and admire. I never wanted to hurt her, ever. She is so fragile and sweet.

i am confused. I have no one to talk to. I have tried to talk to her about this, but she just tells me that she can not relate. I thought maybe she could since she has dated men in attempt to be straight, but she explained how it is not the same thing.. which i still do not fully understand.

We are not communicating. We obviously have become really good at ignoring the obvious.

I am really scared she is going to hate me, that our friends will hate me, that everything we have built together is going to fall apart. I am really scared.

I do not want to live without this person in my life.

I am a wreck and I just feel like there isn't a single person in my life that understands.

I need help. I need guidance.. I need someone to talk to her, and she isnt here.