I'm married but I'm in love

I need someone to talk to about this, but I don't have any one I can come clean to. I figured that this is fairly anonymous so here we go.

I've been married for two years. I have lived with my husband for none of that time. In the past few months he has been distant. His time in the military is coming to an end and he's scared. He has no prospects as far as future employment and I totally get that. He apologizes for being distant and says he's distant from everything right now, but I know that is not true. He is with one of his work friends 24/7.

Meanwhile, I'm in graduate school for physics. I love science and my work. In the time my husband has been distant however, I have grown closer to another student. We are almost the same in every way. Even down to an embarrassing OCD habit we both have. I've shared this, my darkest secret, and many other secrets with him. He loves science and has an amazing sense of humor and he's told me that he's in love with me.

It was not supposed to come to this and I don't know what to do. This is the most irrational sent of feelings that I have ever had in my life and for the first time I don't know what to do. Let me reiterate, I AM NOT cheating on my husband. I care about him and don't want to hurt him, but I'm not sure if that will cost me happiness. I have no idea how to proceed.....