BlindCourage : Welcome! Unfortunately, it is true that there's a relatively small set of SOs who post here, and I apologize for being slow to post, as well. (In part because there are so few of us here, I'm afraid I do tend to spend more time in other support groups these days.) I had also been married just about 9 years when my wife dropped this bomb on me; the difference is that she did NOT figure it out until just before she told me. Feeling betrayed and lied to is absolutely normal and even typical when your spouse hides something of this magnitude from you. So is being angry, afraid, anxious, stressed out, and generally feeling like your life is turned upside down... it can get easier, but right now it's completely to be expected that you're on a roller coaster of emotions (including and sometimes especially rage or grief). One piece of advice I always give SOs right away is that they *do* need space to feel what they feel, and that letting it be all about the trans person is detrimental to the relationship.
In your case, unlike mine, you're very clear on what your dealbreakers are. That's good, in that it lets him make decisions for himself in full knowledge of the costs (and rewards), and it's also good for you because it means you have a strong sense of yourself and your own limits. In fact, and I much more rarely say this, I will caution you against getting too entangled in supporting his transition just yet. There's no way of knowing where his train will take him, and even less of knowing whether or not you can believe what he tells you about that (because he's already lied and concealed things once, and regardless of how valid and powerful his reasons were, that means you can't trust him on this subject). If GRS alone is the breaking point, well, many trans people do not choose to do that. If presenting full-time as a woman is also a dealbreaker, and for a straight woman who is as certain as you are I think it might be, you may want to brace yourself for the possibility that that is what he ultimately will want.
Fundamentally, he can no more ask you to change your orientation than you can expect him not to be trans. (Some straight people do turn out to be more flexible than they or their partner realized, but that's not something anyone else can ASK for.) It's one of the tragedies of transition that sometimes relationships founder on precisely that fact. Good luck, and remember to take time to focus on yourself.
