Yes, in a way, he was lying to you. Along with everyone else in the world, and to himself for a long time, too, probably. Don't take it personally. Look at the way you're feeling now, the confusion, fear, perhaps feeling of betrayal - and then recognize that he probably knew you would react that way. But having been together for two years, he loves you and trusts you enough to tell you something that is monumentally horrifying to admit in the beginning. Having to look someone you love in the eye and tell them something that could easily have them turn around and never come back, something that most of society doesn't understand and is hostile to, is not easy in the least.
There is a lot to read here. You may have more success reading in the transsexual/transgender/male to female forums, to try to get a grasp of what our situation means to us. But certainly poke through the significant other threads here. You are not alone in your position. And yes, it is unfair to have this dropped in your lap, but the burden that he has carried alone was unfair for him to be born with, too.
Many people here were marines, construction workers, boyscouts, etc - and are now women. Do not underestimate the ability for people to repress and deny and try to fake their way through life, from the feeling of necessity.
Please, try to forgive him for the deception - we usually have no choice in the beginning. He may not have even realized what was going on when he first started seeing you.
Gender and sexuality are very complex things, made worse by the fact that family plays a part for so many people. You can love a person for the person they are, beyond their body. However, if you lose attraction to him as a partner because he becomes increasingly feminine and you are not interested in that, it is not your fault.
Please, never fear to ask questions anywhere here.