So what's the alternative? He continues to be in a relationship with a woman who wants something that he can NEVER give her? That's extremely unfair, don't you think?
I know you don't want to hurt him right now, but think about the long term. You marry, you have children and then you come out and leave a wake of broken hearts behind you--when you could've been honest with yourself and your partner.
To be honest, part of your hesitation is not just that you don't want to hurt him. You don't want to lose the heterosexual privilege of the long awaited relationship that could eventually turn into a marriage and finally validate you as a real woman in the eyes of society. Its not fair to him for you to hold on to him as a convenient prop to protect you from the backlash of living against the expectations of society.
Will he be angry? Oh yes, absolutely. Whether its explosive anger or the quiet anger for his wasted time, and the feeling that he's been lied to or the gnawing sense of inadequacy that he wasn't man enough to keep you straight. Yes, it will ALL COME UP.
That's no reason to shy away or avoid telling the truth. Put your big girl undies on and tell him. If you need a plan and help transitioning into this new identity that is against the grain CLICK HERE to set up a complimentary coaching session with me.