Like my best guy friend?

My best guy friend, Ty, and I see each other every day, all day (we work together). We've become very close friends, and I really love him. At the beginning of our relationship, I had a minor crush on him, but didn't tell him. Then I learned he had a girlfriend and I somehow managed to drop my feelings. Then we became very close and recently the feelings have resurfaced. He still has his girlfriend, but doesn't talk about her as much. I don't want to tell him I like him, because I want to keep my friendship. I don't want him to cheat on his girlfriend, because NOBODY deserves that. And if he'll cheat on her with me, he'll cheat on me with someone else. I just wanted some pointers on how to handle the relationship and my feelings toward him. Anyone?