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