Please guys tell me if I reading this all wrong:
Maybe he doesn't have a hetero side, never did. But repressing his homosexuality, and his father sure help in that, with that nice side show to see Earl's body. If that doesn't make you repress a few things what will? (I don't know if I'm making sense) , Jack came along awaken something in Ennis that was there docile. It caught Ennis unawares, like that punch he gave to Jack. Proclaiming from the outset of their relationship, "I'm not queer", and deep inside saying "hey maybe I am. ", and fighting it from that moment on.
It had to be more in my mind, then the fear of being found out. The battle went too deep, too personal, way too desperate. his violence plays a major factor in his reactions to situations he couldn't handle, finely taught by his father.
That kind of battle could only last so long, without some other underlining factor. I think for Ennis is the realization of his homosexuality was something he couldn't come to terms with until the end, after Jack's death.
His anger, self hate, feeling short changed could be the direct result of his own inability to see who he truly was. He lived his life in the shadows, not staying in one job, living only for the time he would spent with Jack. Even then way out in the middle of nowhere, but not letting go of Jack.
The final confrontation was so telling. Ennis's separates himself from Jack with the "boys like you" remark. Why? Because Jack is more comfortable with who he is then Ennis, and Ennis could never be at that same point?
What I'm trying to and maybe clumsily is that Ennis's battle goes much deeper than just being found out, but avoiding coming to terms with himself, coming out , even to himself.
All of these things created the man that found himself in a situation he couldn't deal with, and resulted in what in the end was a sum total of his life two shirts hanging in a closet.